Connecticut Senator Joe Lieberman is making the rounds telling anyone and everyone that he's opposed to the Finance Committee's health care bill, and indeed probably the entire concept of health care reform. Whatever Lieberman's motivation -- a desire for attention, a desire to protect an insurance industry that has a large presence in his state -- he would seem to be putting his political future at risk by doing so.
Lieberman's approval rating cratered among Democrats in mid-2006, dropping from 60 in May of that year to 38 in August after he lost to Ned Lamont and the U.S. Senate primary and then announced he would seek a re-match as an independent. Although Lieberman's numbers improved among Republicans and held roughly steady among independents over this period, the net effect was a deterioration in his approval rating from the low 60's to the low-to-mid 50's.
Lieberman's numbers held steady in that position for some time, until they dropped significantly further from March to July 2008, probably coinciding with the period when he began to routinely attack then-candidate Barack Obama. (Lieberman had endorsed John McCain in December 2007 in advance of the Republican primaries, but it perhaps hadn't dawned on Connecticut Democrats that he would continue to vocally support McCain during the general election.) During this period, his approval ratings dropped another 15-20 points among Democrats, and 5-10 points among independents -- while ironically not really improving any among Republicans. His overall performance rating bottomed out at 38 percent in December.
Since then, Lieberman's standing has been somewhat rehabilitated, primarily because of improvement among Democrats, with whom his approval rating has climbed back up from the low 20's into the mid-30's. It appears that Lieberman's backing for the stimulus package, rather than the afterglow of Barack Obama's election or the Democrats' decision to allow him to remain in their caucus, was the cause, as the bounce among Democrats occurred between February and March, during which time the stimulus vote occurred.
Generally speaking, this would suggest that Lieberman has more to lose among Democrats than he has to gain among Republicans by bucking his former party, which is only natural since Democrats outnumber Republicans in Connecticut by a 39-32 margin.
Were he to vote against the health care package, or vote to filibuster it, this would just about guarantee that he wouldn't be the Democratic nominee in 2012 would be vigorously and angrily opposed by everyone from the top levels of the Democratic establishment to the netroots. Republicans would then have to decide whether to field a candidate on their own or let Lieberman duke it out with the Democratic nominee, a decision that might depend on whether popular governor Jodi Rell were interested in that seat. Were Lieberman opposed by a credible Democrat on the left as well as Rell on the right, my guess is that he's struggle to emerge with more than 15-20 percent of the vote.
The absence of a strong Republican challenger would make life somewhat easier for him, but a February poll found him losing 58-30 (!) to Democratic Attorney General Richard Blumenthal in a matchup with no Republican candidate.
Although Lieberman will probably face some sort of challenge from his left no matter what, his best chance to remain in office, by far, would seem to be to continue to make nice with the Democratic establishment, to the extent that he deterred a strong challenger like Blumenthal from running against him. That will require him to vote with the Democrats on health care. Indeed, I don't see how Lieberman has any leverage to speak of, although who's to say whether he's looking at this from anything resembling a rational perspective.
Connecticut voters favor the health care package by a 47-42 plurality, according to a Quinnipiac poll conducted in September, with support dividing itself sharply along party lines and independents splitting their preferences evenly. Connecticutians also support the public option, which Lieberman is opposed to, by a more robust 64-30 majority, according to the same poll.