Even before Evan Bayh's retirement, the latest Senate polling showed Democrats teetering between only a 52-48 and 53-47 Senate majority after 2010. With Bayh's retirement, Democrats are now firmly staring at a 52-48 majority.
But, it could get even worse than that for Democrats. Potential Republican Senate recruits in a number of states could even threaten Democratic control of the chamber:
Maryland: If incumbent Barbara Mikulski retires, as a new report is claiming, that would create an open seat in Maryland. Democrats would still be favored to win, but by no means would they be a lock. Mikulski, by contrast, would not have faced any serious opposition.
New York: If former Republican Governor George Pataki were to enter the campaign, he would start 3.5% ahead of Democrat Kirsten Gillibrand, according to the Pollster.com trendline.
Washington: If two-time Gubenatorial loser Dino Rossi were to enter the campaign against Patty Murray, he would start the campaign 2% ahead, according to Rasmussen polling.
If Republicans can indeed put up to four more Senate seats into play, they would indeed threaten control of the chamber itself. They have plenty of time to put this together, too, as all four of these states have filing deadlines in June or later.
There is no guarantee at all that we have hit the bottom yet. Even Democratic control of the Senate after 2010 is somewhat in question.