I get asked about Lieberman/Lamont/Obama a lot, and Greg Mitchell has a good rundown of what happened:

As you may have heard, Lieberman was asked yesterday about Bill Kristol linking Obama to Marx — and we don’t mean Groucho — in his New York Times column yesterday. On the Brian and Judge radio show, asked if Obama was indeed a Marxist, Lieberman replied, "I must say, that’s a good question … I will tell you that during this campaign, I’ve learned some things about him, about the kind of environment from which he came ideologically. And I wouldn’t … I’d hesitate to say he’s a Marxist, but he’s got some positions that are far to the left of me and I think mainstream America."

Yet, just a little more than two years ago, Lieberman, facing a strong threat from antiwar candidate Ned Lamont in the Democratic primary, invited Obama to give a major speech in Connecticut endorsing him for re-election — which some liberals still hold against Obama.

"I am absolutely certain Connecticut is going to have the good sense to send Joe Lieberman back to the U.S. Senate so he can continue to serve on our behalf," Obama proclaimed then.

An AP story in late March 2006 on the event noted that "Lieberman became Obama’s mentor when Obama was sworn into the Senate in 2005. They stayed close at Thursday night’s event, too, entering the room together and working the crowd in tandem." However, "scattered boos greeted Lieberman when he took the podium, and he had to stop three times during his remarks to shush the crowd so he could deliver key points."

So clearly Obama had stuck his neck way, way for Lieberman. But Lieberman may still be smarting from Obama’s decision, at the very end of the 2006 race, to endorse Lamont, who had won the primary, over Lieberman. The latter ran as a third party candidate (and won). Even so, liberals derided Obama for his very modest efforts on behalf of Lamont. Now Lieberman hints there may be something to this "Marxist" charge after all.

Can we just dispense with the charade that Joe Lieberman is doing any of this because he’s a man of principle who will back the best candidate, regardless of party, as he maintains?

Joe Lieberman, whom Chris Durang once called a "sanctimonious Hobbitt," had his ass kicked out of the Democratic party. He’s a petty, bitter, nasty little man and he’s backing John McCain because that represents his own personal political upside.

Outside of an appetite for endless war he doesn’t want to fight himself, ideology has nothing to do with it.