The final Quinnipiac poll of the Pennsylvania Democratic Senate primary shows Jose Sestak leading Arlen Specter by a single point. While a one point lead is far from a blowout or a sure thing, what is significant about this poll is that there are now exactly zero polling firms showing Arlen Specter ahead. Here are the final polls from the six pollsters to conducts surveys of this campaign in May:
Final polls, Pennsylvania Senate primary, May
Across these six polls, Sestak leads by 3.2% on the mean, and 2% on the median. The 15-day average I use for other forecasts shows Sestak up 2.6%.
None of those leads make Sestak anywhere close to a sure thing. However, Specter is only competitive in this primary due to his ongoing advantage in name ID, an advantage which averages 20% across five of these six polls (excluding F & M). That means Specter still has a big advantage among low information voters (who have still never heard of Sestak), and as such will need high Democratic turnout to win (since these low-information voters are less likely to vote). With Democratic turnout sharply down in primaries do far this year, that ain't too bloody likely.
I expect Sestak to win as this point, and to become the first Democrat to defeat an incumbent backed by Obama in a primary. Admittedly, Specter's party switch made this campaign far more winnable than any of the other primary or legislative campaigns when progressives staked out a position to the left of the administration, so it may not really be a breakthrough moment yet. From the very beginning of the campaign, Sestak was always ahead among Pennsylvania Democrats who had heard of both candidate, and he held a 2-1 lead among Pennsylvania Democrats who thought Arlen Specter switched parties to win re-election. In the environment, Sestak did exactly what he had to do to win: run a grueling slog of retail politics and fundraising to gather up just enough ground supporters and resources in order to raise his name ID and run ads of Specter saying he switched parties to win re-election. It wasn't easy to do that with the entire Democratic establishment working against him, but on the eve of the primary it seems likely that he has pulled it off.