Senate Forecast

Senate forecast, August 11th: Only a 0.54% chance of GOP takeover

by: Chris Bowers

Wed Aug 11, 2010 at 19:07

Most likely outcome, with Rasmussen: 52 Dems, 47 GOP, 1 Charlie Crist
Most likely outcome, without Rasmussen: 54 Dems, 45 GOP, 1 Charlie Crist

Of the 100 Senate seats, 87 are either not up for re-election, or have a polling average where one party has a 100% chance of victory (if the election were held today).  Among those 87 seats, there are 48 Democrats, and 39 Republicans.  Here is a chart featuring the other 13 campaigns:

Senate competitive campaigns chart, August 11th

With Rasmussen polls included in the 25-day averages, Dems are projected to win 4.29, or 4, seats, if the election were held today.  Without Rasmussen polls included, Democrats are projected to win 5.83, or 6, seats if the election were held today.  Charlie Crist wins one seat in both projections.

Notably, even though the projected number of seats has changed little over the past six months, Republican chances of taking over the Senate have dropped sharply over the past three weeks.  Given the polling averages above, Republican chances of taking over the Senate would be only 0.54%.  And that is including Rasmussen polls, and if Charlie Crist caucuses with Republicans.

Carly Fiorina's drop in California is almost single-handedly responsible for this decline in GOP chances to win the Senate.  With Barbara Boxer pushing her lead out to 7.0%, both with and without Rasmussen polls, there is only a 3% chance of a Fiorina victory if the election were held today.  This means Republicans would have to sweep the remaining 11 campaigns, and get Crist to caucus with them, in order to take a 51-49 majority in the Senate.  The odds of that happening are very low.

So, if nothing else, Democratic chances of retaining a Senate majority are not only looking very good, but still improving.

Notes:

  • Methodology here
  • All polls taken from Pollster.com
  • * = Has primary challenger, but heavy favorite
  • The "current Dem winning %" column projects the chance of Democratic victory if the election were held today.  It is not meant to predict the chance of the Democratic candidate winning in November.
  • Every Senate seat not listed here currently has either a 0% or a 100% chance of a Democratic victory.
  • Knedrick Meek is projected as the winner of the Florida primary because he leads in 3 of 4 polls, even though Jeff Greene narrowly leads the average.
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Senate Forecast Update, August 9th

by: Chris Bowers

Mon Aug 09, 2010 at 20:26

Senate Picture, August 9th, with Rasmussen
Most likely outcome: Democrats 52 seats, Republicans 47 seats, Charlie Crist 1 seat

Of the 100 Senate seats, 86 are either not up for re-election, or have a polling average where one party has a 100% chance of victory (if the election were held today).  Among those 86 seats, there are 48 Democrats, and 38 Republicans.  Here is a chart featuring the other 14 campaigns:

Senate picture, competitive campaigns chart, August 9th, with Rasmussen

The 48 currently safe Democrats, plus the 4.20 wins projected in these 14 campaigns, comes out to 52.20 Democrats, or 52 seats.  Charlie Crist is also projected to win one seat.

Senate Picture, August 9th, without Rasmussen
Most likely outcome: Democrats 54 seats, Republicans 45 seats, Charlie Crist 1 seat

Senate picture, competitive campaigns chart, August 9th, without Rasmussen

The 48 currently safe Democrats, plus the 6.00 wins projected in these 14 campaigns, comes out to 54.00 Democrats. Charlie Crist is also projected to win one seat.

Notes:

  • Methodology here
  • All polls taken from Pollster.com
  • * = Has primary challenger, but heavy favorite
  • The "current Dem winning %" column projects the chance of Democratic victory if the election were held today.  It is not meant to predict the chance of the Democratic candidate winning in November.
  • Every Senate seat not listed here currently has either a 0% or a 100% chance of a Democratic victory.
  • Knedrick Meek is projected as the winner of the Florida primary because he leads in 3 of 4 polls, even though Jeff Greene narrowly leads the average.
Very little overall change in the numbers from last week, but that really isn't surprising for August.  Outside of the states which still have primaries, the major ad buys will not begin until after Labor Day.  Still, it won't be long before I am posting an update to the forecast every evening.

Also, I ran the 25-day simple mean methodology against another forecasting giant, Real Clear Politics.  Across the 48 Presidential, Senatorial, and Gubernatorial general election campaigns with the closest final polling averages since 2008 where Real Clear Politics made a final projection, the 25-day simple mean was much more accurate:

Real Clear Politics
Mean Error: 2.91
Median Error: 2.14

25-day simple mean
Mean error: 2.39
Median error: 1.65

That's a big gap in accuracy between the two methodologies.

The error being measured is final projected margin to final actual margin. Dave Leip's Atlas of Elections is used as the source for the final margin.  You can see all of the work backing up these claims here.

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The World's Greatest Election Forecast, in the World

by: Chris Bowers

Tue Aug 03, 2010 at 16:00

At long last, I have finally completed all of the research for my 2010 Senate (and, eventually, Governor) forecast methodology.  I am extremely pleased with the results, which I believe show it to be the most accurate methodology produced anywhere.  The methodology is explained below.

But first, here are today's numbers!

Senate Picture, August 3rd, with Rasmussen
Most likely outcome: Democrats 52 seats, Republicans 47 seats, Charlie Crist 1 seat

Of the 100 Senate seats, 86 are either not up for re-election, or have a polling average where one party has a 100% chance of victory (if the election were held today).  Among those 86 seats, there are 48 Democrats, and 38 Republicans.  Here is a chart featuring the other 14 campaigns:

Senate picture, competitive campaigns chart, August 3rd, with Rasmussen

The 48 currently safe Democrats, plus the 4.05 wins projected in these 14 campaigns, comes out to 52.05 Democrats, or 52 seats.  Charlie Crist is also projected to win one seat.

Senate Picture, August 3rd, without Rasmussen
Most likely outcome: Democrats 54 seats, Republicans 45 seats, Charlie Crist 1 seat

Senate picture, competitive campaigns chart, August 3rd, without Rasmussen

The 48 currently safe Democrats, plus the 5.91 wins projected in these 14 campaigns, comes out to 53.91 Democrats, or 54 seats.   Charlie Crist is also projected to win one seat.

Notes:

  • * = Has primary challenger, but heavy favorite
  • The "current Dem winning %" column projects the chance of Democratic victory if the election were held today.  It is not meant to predict the chance of the Democratic candidate winning in November.
  • Every Senate seat not listed here currently has either a 0% or a 100% chance of a Democratic victory.

Senate Forecast Methodology

I strongly believe this to be the most accurate statewide electoral forecasting methodology published anywhere.  Additionally, it is simple enough that almost anyone can reproduce it, no matter their level of background in statistics or polling.  This simplicity also means transparency, as almost anyone can both understand the assumptions I am making and check my arithmetic for accuracy.

The methodology is extremely simple: just take the simple mean of almost all polls that had the majority of their interviews conducted during the final 25 days of a campaign (see the notes below for more info).  That's it.  And it works, too:

Error rates, final predicted margin to final vote margin, 52 closest Presidential, Senatorial and Gubernatorial general election campaigns, 2008-2010
Pollster 538 Simple 25-day mean
Mean error 2.79 2.82 2.55
Median error 2.15 2.16 1.67
In the 52-closest Presidential, Senatorial and Gubernatorial campaigns where final margins were published by both 538 and Pollster.com, the simple 25-day mean resulted in significantly less error.  The 25-day simple mean had 9-10% less error on the mean, and 22-23% less error on the median.  Additionally, it was the most accurate in 21 of those campaigns, and the second most accurate in 19.

Further, the 2008-2010 performance of the 25-day simple mean was not a fluke.  Since 2004, across the 145 closest Presidential, Senatorial and Gubernatorial general election campaigns, its mean error rate has been 2.57, and its median error rate has been 1.76.  That is a consistently strong performance that will be difficult for any methodology to surpass, or even equal.  As of this writing, I know of no methodology that has done so.

Now, in the extended entry, answering some likely questions / objections:  

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Senate Forecast, July 28th: Democrats reach 55 seats without Rasmussen

by: Chris Bowers

Wed Jul 28, 2010 at 23:36

The difference between Rasmussen polling and non-Rasmussen polling has reached new heights in tonight's Senate forecast.  For the first time, the non-Rasmussen forecast shows Democrats performing fully 3 seats better than in the forecast which includes Rasmussen polls.

Senate Picture, July 28th, with Rasmussen
Most likely outcome: Democrats 52 seats, Republicans 47 seats, Charlie Crist one seat

Of the 100 Senate seats, 86 are either not up for re-election, or have a polling average where one party has a 100% chance of victory (if the election were held today).  Among those 86 seats, there are 48 Democrats, and 38 Republicans.  Here is a chart featuring the other 14 campaigns:

Senate picture, competitive campaigns chart, July 28th, with Rasmussen

The 48 currently safe Democrats, plus the 3.79 wins projected in these 14 campaigns, comes out to 51.79 Democrats, or 52 seats.  Charlie Crist is also projected to win one seat.

Senate Picture, July 28th, without Rasmussen
Most likely outcome: Democrats 55 seats, Republicans 44 seats, Charlie Crist one seat

Senate picture, competitive campaigns chart, July 28th, without Rasmussen

The 48 currently sage Democrats, plus the 6.69 wins projected in these 14 campaigns, comes out to 54.69 Democrats, or 55 seats.   Charlie Crist is also projected to win one seat.

Notes:

  • * = Has primary challenger, but heavy favorite
  • Methodology can be found here . No Research 2000 polls were used.
  • The "current Dem winning %" column projects the chance of Democratic victory if the election were held today.  It is not meant to predict the chance of the Democratic candidate winning in November.
  • Every seat not listed here currently has either a 0% or a 100% chance of a Democratic victory.
Democrats are showing a distinct improvement in non-Rasmussen polling over the past two months, even as there has been little overall change within Rasmussen polling.  They are now at 55 seats for the first time in over six months.

As the gap between Rasmussen and non-Rasmussen polls increases, I become more inclined to believe the non-Rasmussen forecast.  Outlying polls, both by definition and by empirical observation, have more error than non-outlying polls.  So, the further away Rasmussen moves from the average of all other polls, the more I think something is wrong with Rasmussen polling.

It wouldn't be the first time.  In the past, Rasmussen has received a significant source of right-wing funding, and then proven to be the least accurate pollster in an election by erring massively in favor of Republicans.

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Senate Forecast, July 26: Without Rasmussen polls, GOP only leads in 43 Senate seats

by: Chris Bowers

Mon Jul 26, 2010 at 13:45

The main story in today's Senate forecast is the re-emergence of a significant difference between Rasmussen and non-Rasmussen polls.  Most strikingly, while Rasmussen has Republicans  ahead (or safe / non up for re-election) in 50 Senate seats, the average of all other polls only shows Republicans ahead in 43 Senate seats.  the seven differing states are Washington, Nevada, Colorado, Wisconsin, Ohio, Pennsylvania, and Florida.

Due to this difference, I have once again started producing forecasts with and without Rasmussen polls.  Here are the numbers:

Senate Picture, July 26th, with Rasmussen
Most likely outcome: Democrats 52 seats, Republicans 47 seats, Charlie Crist one seat
Odds of GOP taking chamber: 1.93% (if the election were held today)

Of the 100 Senate seats, 87 are either not up for re-election, or have a polling average where one party has a 100% chance of victory (if the election were held today).  Among those 87 seats, there are 48 Democrats, and 39 Republicans.  Here is a chart featuring the other 13 campaigns:

Senate picture, competitive campaigns chart, July 26th, with Rasmussen

The 48 currently safe Democrats, plus the 3.83 wins projected in these 13 campaigns, comes out to 51.83 Democrats, or 52 seats.  Charlie Crist is also projected to win one seat.

Senate Picture, July 26th, without Rasmussen
Most likely outcome: Democrats 54 seats, Republicans 45 seats, Charlie Crist one seat
Odds of GOP taking chamber: 0.02% (if the election were held today)

Senate picture, competitive campaigns chart, July 26th, without Rasmussen

The 48 currently sage Democrats, plus the 6.35 wins projected in these 13 campaigns, comes out to 54.35 Democrats, or 54 seats.   Charlie Crist is also porjected to win one seat.

Notes:

  • * = Has primary challenger, but heavy favorite
  • Methodology can be found here . No Research 2000 polls were used.
  • The "current Dem winning %" column projects the chance of Democratic victory if the election were held today.  It is not meant to predict the chance of the Democratic candidate winning in November.
  • Every seat not listed here currently has either a 0% or a 100% chance of a Democratic victory.
Commentary on today's forecast can be found in the extended entry.
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Senate Forecast Update: Dems down to 52 seats, but only 2% chance of GOP winning chamber

by: Chris Bowers

Mon Jul 19, 2010 at 11:49

Today I am introducing a new addition to the Senate picture: the odds of Republicans winning control of the camber if the election were held today.  Hopefully it adds some spice to the forecast:

Senate Picture, July 19th
Most likely outcome: Democrats 52 seats, Republicans 47 seats, Charlie Crist one seat
Odds of GOP taking chamber: 2% (if the election were held today)

Senate picture, competitive seats chart, July 19th

Notes:

  • * = Has primary challenger, but heavy favorite
  • Methodology can be found here.
  • The "current Dem winning %" column projects the chance of Democratic victory if the election were held today.  It is not meant to predict the chance of the Democratic candidate winning in November.
  • Every seat not listed here currently has either a 0% or a 100% chance of a Democratic victory.
This forecast is a step backward for Democrats since Friday., when they were projected at 53 seats. The causes for this are two new polls, both from Rasmussen, in Washington and Pennsylvania.  The Washington poll, showing Dino Rossi up 3%, was particularly damaging, as it knocked a poll showing Patty Murray up 7% out of the averages.  This moved Patty Murray's current odds of winning (if the election were held today) from 86% to 28%, accounting for almost all of the pro-Republican shift.

It is worth noting that my most likely projected outcome for the 2010 elections, 52.1 Democratic seats, is lower than Nate Silver's most recent forecast (53.4 Democratic seats).  However, my odds of Democrats maintaining control of the chamber (98%) are much higher than Nate's (85%).  The latter is the difference between  basing odds on if the election were held today versus projecting odds for victory on November 2nd.  The former is likely due to Nate adjusting for Rasmussen's "house effect" in his model.

Adjusting for "house effect" is the only methodological change I am open to in the Senate picture right now.  This is because adjusting for recentness and / or the size of survey samples would have the ironic effect of reducing the amount of data in the averages.  This goes against the core findings that led to this methodology: the more data, the better.  Adjusting for "house effect" does not have this problem, but I have been unable to find a comprehensive list of the "house effects" for polling firms at the state level for the 2004-2008 period.  As such, I have been unable to conduct the research that would indicate whether adjusting for "house effect" produces more accurate results.

In the end, I am fine with never finding a list of "house effects" for statewide pollsters in 2004-2008, and not adjusting for "house effect."  Adjusting for "house effect" would add a level of complexity to the forecast, something I am loathe to do.  In addition to accuracy, another purpose of this forecast is to be as simple as possible, as simplicity breeds both transparency and democracy.  The greater the number of people who can produce, or at least understand, extremely accurate election forecasts, then the greater confidence in the system and the less forecasting remains the province of professional elites.  That ability to lower the cost of the production and consumption of accurate information is what the Internet is, or at least should, be all about.

Additionally, adding another level of complexity to the forecast does not seem necessary right now.  Just taking the simple mean of all properly conducted polls during the last 15, 20, 25 or 30 days of an election (especially 15 days), was, at least according to the research I conducted late last year, more accurate than either Pollster.com or fivethirtyeight.com in 2008.  

Total error rates, final predicted margin to final vote margin, 52 closest Presidential, Gubernatorial and Senatorial general election campaigns, 2008-2010
Pollster 538 Simple 15-day mean
Mean error 2.79 2.83 2.61
Median error 2.14 2.16 1.77
It may be comparatively simple, but it seems to be effective.  You can download all of the data for this comparison here.

No statistics background necessary.  Just include multiple polls from the same pollster in your averages (if applicable), and use polls a bit further out from Election Day than intuition would suggest.

Now, I don't expect that Charles Franklin or Nate Silver, both of whom I respect quite a bit, will allow their methodologies to stand still.  They may yet develop, or perhaps already have developed, methods that surpass the simple mean method. (To clarify, that means more accurate only for the closest elections, which I define as a projected final polling margin of less than 18.5%).  However, it is unlikely that either of those wizards will ever surpass a 2.6 mean error, and a 1.8 median error, by all that much.  As such, the simple mean methodology should always remain competitive with even the most advanced and most accurate statistical models.  In my opinion, that should a crude model can produce such accurate results is both quite amazing and quite democratizing.

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Senate Forecast Update, July 16: Dems 48, GOP 40, and 12 competitive

by: Chris Bowers

Fri Jul 16, 2010 at 14:00

Senate forecast, July 16th: 52.73 Democratic seats (rounds to 53, up from 52.31)

Range: Democrats 48 seats, Republicans 40 seats, and 12 seats currently unclear

I spent this morning going over the Senate forecast with a fine tune comb.  As a result, I believe I have improved the product significantly.  All errors in terms of polling averages, primary campaigns, and the spelling of candidate names have been removed.  I have also reorganized the forecast so that it now makes more sense at a casual glance.

Competitive Senate campaigns table, July 16
Balance of power
Democrats: 48
Republicans: 40
Competitive: 12



These are the 12 Senate campaigns where, if the election were held tomorrow, current polling suggests an uncertain outcome.   The balance of power before an outcome is determined in these 12 campaigns is 48 Democrats and 40 Republicans:  As such, Democrats need to win only two of these campaigns in order to maintain at least nominal control of the chamber.  To maintain actual control, they need at least 53 seats and filibuster reform.

Florida is listed among these 12 campaigns not only because it is close, but because Independent candidate Charlie Crist has not declared which party he would caucus with if he were to win the seat.  I am currently assuming Crist would caucus with Republicans, but until he declares (or falls behind Republican Marco Rubio by 10% or more), Florida will remain in the competitive campaigns chart.

With 109 days until the election, Senate updates will start to occur far more frequently than once a week.  It won't be long before updates take place daily, or even more than daily.  I will still forecast all elections where the incumbent party does not lead by 18.5% or more, but from now on the most competitive campaigns will receive top billing.

Methodology, notes, and a forecast of seven other, less competitive seats, can be found in the extended entry.

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Senate Forecast Update, July 14th: Coming to terms with Rasmussen

by: Chris Bowers

Wed Jul 14, 2010 at 12:14

Senate forecast, July 14th: 52.31 Democratic seats (rounds to 52, up from 51.94)

The latest Senate forecast shows Democrats maintaining only a narrow majority in the upper chamber, 52-48 (with Lieberman caucusing with Democrats and Crist caucusing with Republicans). It includes all polls conducted over the past 30 days, including Rasmussen polls.  At least for now, I am no longer going to separate the forecast into "all polls" and "all non-Rasmussen polls."

This decision is based on new work by David Shor, who finds that while Rasmussen has a huge "house effect" for the generic congressional ballot, the firm is only displaying a house effect of Republican +2 in Senate polling. Even though I have not run the numbers, that also feels right on an intuitive level.  Apart from a few surveys conducted the day after primary elections, recent Rasmussen polling has not been significantly divergent from other Senate polling in the most meaningful Senate campaigns.  This is the case in California, Colorado, Illinois, Kentucky, Missouri, Nevada, Ohio, Pennsylvania, Washington and Wisconsin. As such, right now I think removing Rasmussen polls would create a less accurate forecast, not a more accurate one, as it would remove too much data from the overall projection (about 50% of the data, in fact).

A 2% swing toward Republicans is not inconsequential, especially with 9 campaigns currently showing a margin of 3.5% or less.  Also, it is possible that Rasmussen could start producing a large number of outlying polls again, in the event of which I would produce forecast both with and without Rasmussen polls.  But, at least for now, the Rasmussen effect does not seem to be a big deal, and I am OK with my  projections potentially being slightly on the pessimistic side for Democrats.  It is always good to be prepared for the worst.

On the chart below, right now I define ten campaigns as clearly winnable by either party.  In order of their current winnability for Democrats, those ten campaigns are: Washington, California, Wisconsin, Illinois, Ohio, Pennsylvania, Missouri, Kentucky, Nevada and Colorado.  The outcome of every other campaign is going to be very difficult to change at this time (including West Virginia, given that Manchin seems likely to run).  Still, that produces a wide range of 48 to 58 Senate seats for Democrats, a range which runs the gamut from a total disaster to a massive triumph.

As much impact as the overall political environment has on elections, there are so many close elections right now that the effectiveness of the Democratic operation in those ten campaigns will largely determine whether Democrats can still govern in 2011-2012.  If Democrats can hold the House, win 55 or more Senate seats, and if the brunt of the losses fall on the center-right of the party--an outcome which is entirely plausible at this point--Senate procedural reform would actually make the Democratic majority just as effective, if not more, in 2011-2012 than it has been in 2009-2010. That would be a remarkable victory in the current political and economic environment, and something worth aiming for over the next four months.

Senate forecast overview, July 14th
All Polls Dems GOP
Not up for election 41 23
Incumbent party safe 6 10
Sub-total 47 33
Current polling 5.31 14.69
Projected total 52.31 47.69

The 20 Senate seats that might switch partisan control
The chart below looks only at a broadly defined definition of "competitive" campaigns.  Campaigns where incumbent party currently leads by 18.5% or more are considered "safe" and not listed.  All polls can be found at Pollster.com and Wikipedia.


Notes:

  • * = Has primary challenger, but heavy favorite

  • Methodology can be found here

  • The "current Dem winning %" column projects the chance of Democratic victory if the election were held today.  It is not meant to predict the chance of the Democratic candidate winning in November.

  • Yes, I am projecting J. D. Hayworth to win the Republican primary in Arizona, even though McCain leads in the polls.

  • This forecast includes polls that were released today (July 14th)

  • Florida only remains on the board because there is an off-chance Charlie Crist will caucus with Democrats
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West Virginia likely, but not certain, to stay in Democratic hands

by: Chris Bowers

Fri Jul 09, 2010 at 10:56

Now that there will be an election in November for Robert Byrd's former Senate seat in West Virginia, Democratic Governor Joe Manchin said today it is "highly likely" he will run for the seat:

West Virginia Gov. Joe Manchin said Friday on MSNBC's "The Daily Rundown" that he will probably be a candidate for the late Sen. Robert Byrd's seat in the event there's a special election.

"It's highly likely I will be," he said, describing the process for holding a special: "The direction we're going right now is there is going to be a primary. I'm understanding that the opinion from the attorney general is the governor will select the time for the primary and the general. I believe in the power of the voters who have the right to select who will represent them."

If Manchin does run, it is likely he will win.  Even according to Rasmussen, he leads his closest potential challenger, and the strongest possible Republican recruit in West Virginia, Shelly Moore Capito, by 14%.  Against everyone else, he leads by more than 2-1.

Numbers like these might even be enough to keep Capito from running, which would end the campaign before it began.  Why give up a fairly safe seat in the House for a longshot run at the Senate, especially when Republicans are headed to big gains in 2010?

All in all, right now it sure looks like Democrats dodged a bullet in West Virginia.  Of course, as we saw in Massachusetts, anything can happen.  Still, expect Manchin to appoint himself over the weekend, cast the deciding votes on Wall Street reform and unemployment extension next week, and handily win election in November.

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Senate Forecast, July 6th: Senate definitely in play

by: Chris Bowers

Tue Jul 06, 2010 at 13:50

After five weeks, the Senate forecast is back.  Given current polling controversies, all Research 2000 polls have been removed.  Additionally, the forecast is presented both with and without Rasmussen polls.  Here are the numbers:

  • Senate forecast, July 6 (all polls): 51.94 Democratic seats (rounds to 52, down from 53.43)

  • Senate forecast, without Rasmussen: 54.28 Democratic seats ( rounds to 54, down from 54.37)
The removal of Research 2000 has increased Rasmussen's overall percentage in the "all polls" forecast.  This has in turns increased the gap between the Rasmussen and non-Rasmussen forecast (now a whopping 2.34 seats).  If you are wondering why I consider Rasmussen fishy this year, I explained why on April 19th.

Even without Rasmussen polls, the Senate is definitely in play.  Republicans are ahead, tied, or within 2% of a total of 51 seats, even when there are no Rasmussen polls in the average.  At the same time, Democrats have a realistic chance at 58 seats. Much will hang in the balance of the quality of the campaigns, and the slight changes in the political environment.

Senate forecast overview, July 6th
All Polls
All Polls Dems GOP
Not up for election 41 23
Incumbent party safe 6 10
Sub-total 47 33
Current polling 4.94 15.06
Projected total 51.94 48.06

Without Rasmussen
Without Rasmussen Dems GOP
Not up for election 41 23
Incumbent party safe 6 10
Sub-total 47 33
Current polling 6.67 15.33
Projected total 52.67 47.33
Notes: Because they caucus with Senate Democrats, Independents Bernie Sanders and Joe Lieberman are considered Democrats.  For now, Charlie Crist is considered more likely to caucus with Republicans, and as such is included in the GOP's overall total.

The 20 Senate seats that might switch partisan control
The chart below looks only at a broadly defined definition of "competitive" campaigns.  Campaigns where incumbent party currently leads by 18.5% or more are considered "safe" and not listed.  All polls can be found at Pollster.com and Wikipedia.


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Senate forecast update: Democrats making big gains during primary season

by: Chris Bowers

Thu Jun 03, 2010 at 12:36


June 3rd update: Democrats 53.43 seats
May 28th: Democrats 52.67 seats

While the tea party wave in Republican primaries is dragging down GOP hopes in the 2010 Senate elections, progressive primaries are actually improving Democratic chances.  The net result is that Democrats are making big gains on Republicans during the 2010 primary season.

Since April 14th, Republicans have slid backwards in the general election polling averages in 10 of the 12 states that have featured both competitive primaries and competitive general elections. The average general election loss for Republicans has been significant: 3.7% on the mean, and 4.9% on the median.

Here are the changes in those 12 states.  The April 14th Senate forecast can be seen here, and the current Senate forecasat is in the extended entry of this article:

Change in Republican general election position, Senate campaigns, April 14-current
12 states with competitive primaries and general elections
State Republican loss
Nevada 14.2%
Florida* 10.2%
Iowa 7.0%
North Carolina 6.1%
Pennsylvania 5.2%
California 5.0%
Kentucky 4.7%
Ohio 3.0%
Colorado 2.7%
Arizona** 2.0%
Indiana -5.5%
Arkansas -9.8%
* = Compares mid-April status of Rubio vs Meek general election to current three-way standings
** = For both April and current forecasts, J.D. Hayowrth is considered to be the likely Republican nominee in Arizona, not John McCain

These nearly across the board improvements for Democratss come during a time when Democrats have not improved their standing nationally.  According to Pollster.com, President Obama's net approval rating has dropped by about 2.5% since mid-April, and the national, generic congressional ballot has been stagnant, with perhaps a slight GOP gain.  In other words, Democrats are improving in these states due to local campaign developments, not national trends.

A reasonable conclusion from this is that Republicans are being hurt by their primaries, while Democrats are benefiting from their primaries.  This is as strong as any evidence yet available that the tea party wave in Republican primaries is a decided, net negative for the Republican party..

By contrast, Democrats have seen improvements as a result of their competitive primaries in Kentucky, North Carolina, Ohio, Pennsylvania, and possibly Colorado (although in that case the Democratic improvement is more likely due to Jane Norton's emerging weakness).  The only exception appears to be Arkansas, although Bill Halter's position against John Boozman has only deteriorated by 1.0% over the past two months, if the recent, absurd Rasmussen poll is removed from the averages. Blanche Lincoln's position has entirely collapsed.

The only clear case where Republicans were helped by a primary is in Indiana.  In that state, the Democratic primary was brilliantly cleared by Evan Bayh's late retirement announcement, thereby allowing Republicans to suck up all media attention and get a boost as a result of their competitive primary.  Oh yeah, and two tea party candidates were defeated by the establishment GOP choice in Indiana, too.

The tea party and other right-wing primary efforts are eroding Republican chances in the general election, while progressive efforts are doing exactly the opposite on the Democratic side.  This primary season has been a tremendous help to  Democratic Senate chances.  In fact, without Rasmussen polling, Democrats now lead in enough campaigns to hold 55 seats in the Senate, which is a long way from an electoral disaster.

Complete Senate forecast can be found in the extended entry.

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Senate forecast update: Democrats up to 53 seats for the first time in four months

by: Chris Bowers

Fri May 28, 2010 at 11:00

May 28th forecast: Democrats 53 seats

The five polls from yesterday (and the Mason-Dixon poll from Nevada this morning, the Ohio poll this morning, and the two Daily Kos polls coming out today, which are included in the averages), have promoted a full Senate update this morning.  Polls are typically not conducted over holiday weekends like these, so it is quite possible that there will not be another update for another week.

Man, I wish someone other than Rasmussen had polled Wisconsin.  There are good reasons to think this poll is really hinky.

Still, the forecast is the best for Democrats in four months, and the situation will only continue to improve.  As we get closer to November, Rasmussen polls will occupy a smaller percentage of all polls.  With their 7% "house effect," that will more than cancel out any switchover to likely voters.  This is because the current forecast is closer to the Rasmussen-only average than to the average of all other polls combined.  The closer the election, the closer it will move toward the non-Rasmussen forecast, as Rasmussen polls make up a smaller and smaller percentage of the overall polls.

While in most cases my projected primary winners are ahead according to recent polling, I made exceptions in the case of Nevada and Arizona.  I just can't see Sue Lowden or John McCain surviving the teabagger wave, given their current weak positions.

Also, before anyone in the comments says anything, the win percentages are if the election were held today, not the projected win percentages for winning in November.

Finally, keep in mind that it is entirely possible for Democrats to improve their position in the Senate after 2010.  All that requires is 54 seats or more (to cancel out Ben Nelsen, Joe Lieberman, and Mary Landrieu), plus filibuster reform.  That is an achievable goal.

Today's forecast only looks at general elections, but primaries will return to the forecast next week.  Today, I removed the primaries to provide a clear view of where the overall picture stands.

Senate forecast overview, May 28th
Dems GOP
Not up for election 41 23
Incumbent party safe 5 9
Sub-total 46 32
Current polling 6.67 15.33
Projected total 52.67 47.33
Notes: Because they caucus with Senate Democrats, Independents Bernie Sanders and Joe Lieberman are considered Democrats.  For now, Charlie Crist is considered more likely to caucus with Republicans, and as such is included in the GOP's overall total.

The 22 Senate seats that might switch partisan control
The chart below looks only at a broadly defined definition of "competitive" campaigns.  Campaigns where incumbent party currently leads by 18.5% or more are considered "safe" and not listed.
State Democrat Republican Margin Current Dem Win %
Connecticut Blumenthal McMahon D 15.0 100%
Oregon Wyden Huffman D 13.5 100%
California Boxer Fiorina D 7.0 97%
Washington Murray Rossi D 3.0 83%
Wisconsin Feingold Johnson* D 2.0 77%
Ohio Fisher Portman D 1.0 67%
Nevada Reid Angle D 0.5 58%
Pennnsylvania Sestak Toomey R 0.5 42%
Colorado Bennet Norton R 2.0 23%
North Carolina Marshall Burr R 4.5 9%
Illinois Giannoulis Kirk R 6.5 4%
Missouri Carnahan Blunt R 7.0 3%
Kentucky Conway Paul R 8.2 2%
Arizona Glassman Hayworth R 8.5 2%
Iowa Conlin Grassley R 11.0 0%
New Hampshire Hodes Ayotte R 11.0 0%
South Carolina Rawl DeMint R 13.0 0%
Indiana Ellsworth Coats R 15.5 0%
Arkansas Halter Boozman R 17.8 0%
Florida M 16.2 R 33.2 C 35.4 0%
Delaware Coons Castle* R 20.5 0%
North Dakota Potter Hoeven R 47.0 0%
 

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Rasmussen vs non-Rasmussen Senate forecast

by: Chris Bowers

Thu May 27, 2010 at 09:43

How much is Rasmussen polling influencing the outlook on the 2010 Senate elections?  To find out, I produced updated three forecasts this morning: one without any Rasmussen polls, one with only Rasmussen polls, and one with all polls.  Here are the results:

The 22 Senate seats that might switch partisan control
The chart below looks only at current primary campaign leaders.  Campaigns where incumbent party currently leads by 18.5% or more are considered "safe," and not listed.
State No Rasmussen Rasmussen All Polls
Connecticut D 20.0 D 8.0 D 14.3
Oregon None D 13.5 D 13.5
Wisconsin D 14.5 D 7.5 D 10.5
California D 7.0 D 5.5 D 7.0
Washington R 3.0 D 2.0 D 3.0
Ohio D 3.5 R 2.0 D 2.0
Pennnsylvania R 2.7 D 1.0 R 1.2
Colorado D 1.5 R 6.0 R 2.0
Nevada D 1.5 R 14.0 R 3.3
North Carolina R 3.5 R 13.0 R 4.5
Illinois R 6.5 R 6.0 R 6.5
Missouri Even R 7.0 R 7.0
South Carolina R 7.0 None R 7.0
Arizona* D 1.0 R 12.5 R 8.5
Kentucky R 2.0 R 17.0 R 9.3
Florida I 5.7 R 2.0 I 2.6
Iowa R 15.0 R 16.0 R 11.0
New Hampshire R11.0 R 12.5 R 11.0
Indiana R 8.0 R 18.0 R 15.5
Arkansas R 16.5 R 26.0 R 20.0
Delaware R 15.0 R 22.0 R 20.5
North Dakota R None R 47.0 R 47.0
Methodology
* = In Arizona, I am currently projecting J.D. Hayworth to be the Republican nominee

Here are the projected Democratic seat totals for all three of these forecasts:

  • No Rasmussen: 54.37
  • Only Rasmussen: 51.69
  • All polls: 52.49
At first glance, Rasmussen appears to be weighing down the projection quite a bit.  The overall forecast (52.49 Dems) is significantly closer to the Rasmussen-only projection (51.69 Dems) than to the non-Rasmussen projection (54.37 Dems).

For the 19 campaigns where there is a comparative trend, the Rasmussen poll average shows Republicans performing much better than the average of all other polls.  The median pro-Republican house effect is 7.0%, and the mean is 6.4%.  The difference is by no means consistent, as Rasmussen actually shows Democrats performing better in Pennsylvania and Washington than do other polls, and about the same as other polls in California, Iowa and Illinois.  As such, just tacking on 6.4%, or 7.0%, to the Democratic candidate in Rasmussen polls would not likely increase the accuracy of an election forecast.

Personally, I am still going to stick with the average of all polls, for now.  In the meantime, I will be conducting some research to see if weighting polls by "house effect" would have produced more accurate forecasting results in the 2004, 2006 and 2008 elections.  If it does, then I will start weighting polls by house effects.  If it does not, then I won't.

Discuss :: (7 Comments)

Morning Senate election news, CT, SC, CA: Simmons drops out, DeMint in trouble, Fiorina surges (?)

by: Chris Bowers

Tue May 25, 2010 at 09:31

The 2010 Senate picture continues to get wilder this morning.  Three updates:

  1. Connecticut; Rob Simmons has dropped out of the Republican primary, leaving WWE magnnate Linda McMahon to face Richard Blumenthal. Yesterday, Blumenthal apologized for exaggerating his military record.  He still has a lead in the polls, but nowhere near the commanding, 30-point leads he once held.

  2. South Carolina: The first trial heat poll out of South Carolina shows Republican incumbent and conservative movement icon Jim DeMint leading Democrat Vic Rawl by only 50%-43%. The only other poll on this campaign had been a generic ballot test from early December, showing DeMint up by 9%, with a lot of voters thinking DeMint spent too much time endorsing conservative candidates nationwide rather than paying attention in South Carolina.  So, the poll is believable, and DeMint likely is in some trouble (until Rasmussen shows him up by 27% next week).

    This campaign goes up on the competitive seats chart.  The current winning percentage for Rawl sstarts at 3%.  That figure is if the election were held today, and is not a projection on the future trends of the campaign.

  3. California: In a hard to believe poll, Survey USA shows Carly Fiorina ahead by 23% in the Republican primary in California (and Meg Whitman back ahead by 27% for Governor).  This poll isn't like any of the others on the campaign so far, but combined with the others it actually gives Fiorina a 1.3% lead in the primary..  If Fiorina does win the Republican nomination,that is good news for Barbara Boxer.  While Boxer only leads Tom Campbell by 4.7% (92% current win %), she leads Fiorina by 8.3% (98% current win %).
All told, these updates improve the Democratic position in the overall forecast by 0.09 seats, for a new total of 52.17 seats.  This is another high, post-Evan Bayh's retirement, for Democrats in the Senate forecast.
Discuss :: (1 Comments)

Senate forecast update: Even with Rossi's entry, Dems still in best position since early February

by: Chris Bowers

Mon May 24, 2010 at 18:30

Senate Forecast update, May 24th
  • Total Democratic seats: 52.08 (rounds to 52, down 6.92 from current)
  • Change from May 19: Democrats up 0.01 seats.
The past week has featured a lot of wild Senate news, meriting another update in the overall forecast.  From post-primary polling in Arkansas, Kentucky and Pennsylvania, to pre-primary polling in California and Nevada, to the Blumenthal scandal in Connecticut, and now to Dino Rossi's likely entry into the Washington Senate campaign against Patty Murray, quite a few things have changed.

Oddly enough, the changes appear to almost precisely cancel each other out, resulting in virtually no change from the May 19th update.  Democrats experienced marked improvement in California, Pennsylvania and Nevada, which offset their backslides in Washington and Kentucky.   Overall, the last time Democrats were in a better position than this was on February 11th.

Note that I am now projecting J.D. Hayworth as the winner of the Republican nomination in Arizona, despite John McCain holding a 11.7% lead over the last three polls of that primary.  The reason for this is that a lead of 11.7% is a pretty bad starting point for an incumbent, much less a former Republican presidential nominee.  With numbers like that, my gut tells me there is no way McCain survives the anti-incumbent and teabagger waves this year.

Thirteen campaigns, from Wisconsin through Kentucky in the chart below, are really and truly competitive right now.  If Democrats were to somehow sweep them all, they would actually gain a seat, and take 60 going into 2011.  If Republicans were to capture them all, they would take a 53-47 majority in the Senate.  This means both that control of the Senate is in play, and also that a huge amount will depend on the quality of individual campaigns from here on out.

Senate forecast overview, May 24th
Dems GOP
Not up for election 41 23
Incumbent party safe 6 10
Sub-total 47 33
Current polling 5.08 14.92
Projected total 52.08 47.92
Notes: Because they caucus with Senate Democrats, Independents Bernie Sanders and Joe Lieberman are considered Democrats.  For now, Charlie Crist is considered more likely to caucus with Republicans, and as such is included in the GOP's overall total.

The 20 Senate seats that might switch partisan control
The chart below looks only at a broadly defined definition of "competitive" campaigns.  Campaigns where incumbent party currently leads by 18.5% or more are considered "safe" and not listed.
State Democrat Republican Margin Current Dem Win %
Wisconsin Feingold Wall* D 11.5 100%
Connecticut Blumenthal McMahon D 9.0 99%
CT Blumenthal Simmons D 17.0 100%
CT R Primary McMahon Even
California Boxer Campbell D 4.7 92%
CA Boxer Fiorina D 8.3 98%
CA Boxer DeVore D 8.7 98%
CA R Primary Campbell +6.0
Washington Murray Rossi* D 2.0 77%
Ohio Fisher Portman R 0.3 45%
Pennnsylvania Sestak Toomey R 1.2 32%
Colorado Bennet Norton R 2.0 23%
CO Romanoff Norton R 2.5 20%
CO Bennet Buck R 0.5 30%
CO Romanoff Buck R 1.0 33%
CO D Primary Bennet +10.5
CO R Primary Norton +11.0
Nevada Reid Lowden R 3.3 15%
NV Reid Tarkanian R 4.0 11%
NV Reid Angle R 5.5 6%
NV R Primary Lowden +6.0
North Carolina Marshall Burr R 4.5 9%
NC Cunningham Burr R 9.0 1%
NC D Primary Marshall +2.5
Arizona Glassman Hayworth R 4.7 8%
AZ Glassman McCain R 19.3 0%
AZ R Primary McCain +11.7
Illinois Giannoulis Kirk R 6.5 4%
Missouri Carnahan Blunt R 7.0 3%
Kentucky Conway Paul R 9.7 1%
Iowa Conlin* Grassley R 11.0 0%
New Hampshire Hodes* Ayotte* R 11.0 0%
Indiana Ellsworth Coats R 15.5 0%
Florida M 17.8 R 31.5 C 34.3 0%
Arkansas Halter Boozman R 20.0 0%
AR Lincoln Boozeman R 23.0 0%
AR D Primary Halter +2.0
Delaware Coons Castle* R 20.5 0%
North Dakota Potter Hoeven R 47.0 0%
Notes in the extended entry.

There's More... :: (17 Comments, 117 words in story)
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