Over the past six months, our polling partners at PPP have provided a pretty awesome resource. They have compiled fairly recent approval numbers for nearly two-thirds of the U.S. Senate, including over a dozen Senators up for re-election in 2012.
On paper, 2012 should be a pretty tough year for Democrats in the Senate, despite the prospects for a rebound election in the wake of November's defeats. The Democrats, as often happens in Senate election cycles, are victims of their own success: their excellent performance in 2006 means that the Democrats have a far bigger class of Senators to defend in 23 months.
So, who is looking particularly vulnerable heading into the cycle. The three candidates in the most dire straits consist of one Republican, one Democrat, and one...um...whatever the hell Joe Lieberman is.
Approval ratings, candidates facing re-election in 2012, Lowest three
Joe Lieberman (I-CT): 33/54 (-21 net approval)
John Ensign (R-NV): 41/48 (-7 net approval)
Bob Casey (D-PA): 36/40 (-4 net approval)
Lieberman's problem, according to PPP's Tom Jensen, is the same problem confronted by another hugely unpopular Senator (outgoing Pennsylvania Senator Arlen Specter):
Specter and Lieberman's numbers definitely speak to the perils of having it both ways...they don't really make Democrats or Republicans particularly happy and you can get away with that if independents love you for your independence but in their cases that has not happened.
Jensen does wonder aloud if Lieberman's leadership role on DADT repeal has put him back in good stead with Democrats, and promises to poll the state again in the near future. Lieberman's forced retirement could grow more likely if Linda McMahon decides to make another Senate bid. She has shown signs of doing so, and if she does, Lieberman cannot rely on Republican votes to save him the way that they did in 2006.
Given Ensign's travails, a net negative approval of seven points is actually not all that bad. That said, it seems pretty unlikely that Ensign survives the 2012 campaign. Indeed, his fate may well get sealed in the GOP primary, where he is almost certain to face a high profile battle. The most likely intraparty rival for Ensign looks to be upstate Congressman Dean Heller, who may well have the tacit backing of both Nevada and DC Republicans.
While Casey's numbers are not awful, they are mediocre in a state that was an unmitigated disaster for Democrats in 2010. His saving grace may well be the absence of an obvious first-tier challenger. The GOP's best bet might be suburban Congressman Jim Gerlach, but life in the majority might suit him well, and make him less likely to move, especially since the GOP now controls the redistricting process in the state.
Other incumbent Senators who might get targeted comprise a quartet of Democrats whose approval ratings range from a net approval of -1 to +4. They are: Bill Nelson (FL), Debbie Stabenow (MI), Claire McCaskill (MO), and Sherrod Brown (OH). Democrats have to hope that the electorate in the four key states represented by those Senators behave like they did in 2008 (when President Obama came with 10,000 votes of sweeping them) than they did in 2010, when the GOP dominated in these four states.
On the other end of the spectrum are the four most popular Senators up for re-election in 2012. Among those polled by PPP, the four top dogs split evenly between the Democrats (Minnesota's Amy Klobuchar and New Mexico's Jeff Bingaman) and the GOP (Maine's Olympia Snowe and Massachusetts' Scott Brown). Of the four, only Brown is likely to get targeted, if only because of the natural terrain in the Bay State.