I find this incredibly hard to believe. Lieberman's numbers have been consistently negative in Connecticut since his last re-election; in fact, I remember polls only months after the election showing that Ned Lamont would win a rematch handily. I can easily see all of Joementum's backstabbing and sudden shifts in position being cynical plays in the service of some crazy re-election strategy, but for the life of me I can't figure out what that strategy would be. It truly escapes me how campaigning for Republicans and against Barack Obama and the public option could possibly benefit Lieberman electorally, unless he thinks he can still split the Democratic vote and win over the GOP like in '06. Even still, the path of least resistance is obviously Joe securing the Democratic nomination.
I suppose the more plausible explanation is that Lieberman's head has gotten so bloated from all the years in the Senate, the VP nod in 2000, the victory in '06, and all the media attention since, that he must think he's untouchable. The polls are meaningless, as the Democrats wouldn't dare try something in 2012 after what happened last time. Besides, by then he will have beaten down President Obama so completely that it will be a Republican wave year and he'd coast over any liberal opposition.
I sincerely hope his people are doing their best to convince him how crazy this is. Better yet, I hope they aren't.