Actually, on second thought, I don't think I would hesitate. From Fox News:
FOX'S ANDREW NAPOLITANO: Hey Sen. Lieberman, you know Barack Obama, is he a Marxist as Bill Kristol says might be the case in today’s New York Times? Is he an elitist like your colleague Hillary Clinton says he is?
LIEBERMAN: Well, you know, I must say that’s a good question. I know him now for a little more than three years since he came into the Senate and he’s obviously very smart and he’s a good guy. I will tell ya 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.
From Bill Kristol's pen to Joe Lieberman's mouth: The likely Democratic nominee for president "might be" a Marxist. Somehow I don't think Connecticut voters thought this is what Lieberman meant in 2006 when he described himself, ad nauseum, as a "loyal Democrat."
* I'd forgotten this.