As for what comes next, many liberals are pushing for Reid to strip Lieberman of his seniority and his committee chairmanship, if he joins a GOP filibuster of the health care initiative. But Reid is unlikely to take any such move because Lieberman's vote is critical on so many matters not related to health care.
If that can't happen, some are arguing that Democrats just ignore Lieberman, and instead put their focus on passing a health care bill through the budget reconciliation process, where only 50 votes would be necessary. But that's not the preferred White House strategy, and arcane budget rules could limit what might be accomplished inside the budget process.
Lieberman's next political move is unclear. He's up for reelection in 2012 but it's not certain whether -- or how -- he would run for reelection.
Asked by ABC's Jonathan Karl in October whether he'd run as a Democrat in 2012, Lieberman said, "That's an open question."
Liberal activists say that if he seeks another term, they'll finish what they started in 2006.
"I kind of see him as dead man walking in Connecticut," said Green, whose Progressive Change Campaign Committee stands ready to support would-be challengers.
In the meantime, Lieberman benefits from the simple fact that Democrats need him, even if many of them don't like him. He might be among the few political figures who comes out of the grueling health care debate with a smile.
"Transformational reforms need the broadest support possible," said the Democratic Leadership Council's From, who served as a top aide in the Clinton White House. "He's doing the right thing. It's at a time that they need it -- they really do need it."