Independent Senator Joseph Lieberman made a splash on Sunday after he announced he would not support a Medicare buy-in compromise intended to gain votes from a handful of moderate senators.  Democratic leaders have been courting Lieberman for months — but he  has not agreed to their terms.

And Democrats are angry. Huffington Post’s Sam Stein reports “More than 80 percent of Democrats say they believe Sen. Joseph Lieberman (I-Conn) should be stripped of his powerful chairmanship in the Senate if he ends up supporting a Republican filibuster of health care reform, according to a new poll.”

A frustrated Ezra Klein is definitely one of the 80 percent:

To put this in context, Lieberman was invited to participate in the process that led to the Medicare buy-in. His opposition would have killed it before liberals invested in the idea. Instead, he skipped the meetings and is forcing liberals to give up yet another compromise. Each time he does that, he increases the chances of the bill’s failure that much more. And if there’s a policy rationale here, it’s not apparent to me, or to others who’ve interviewed him. At this point, Lieberman seems primarily motivated by torturing liberals. That is to say, he seems willing to cause the deaths of hundreds of thousands of people in order to settle an old electoral score.

Andrew Sprung on Andrew Sullivan’s blog says Lieberman’s announcement means “the Gang of 10’s compromise is dead and that a bill can’t get through the Senate with either a public option or Medicare expansion. Unless Lieberman makes one more grandstanding reversal. Or all of Barack Obama’s courting of [Maine Sen. Olympia] Snowe pays off somehow.  Or Susan Collins has an epiphany. Or someone resigns abruptly and Santa is appointed to the Senate.”

The New Republic’s Jonathan Cohn picks out another reason Lieberman may oppose the compromise: “Lieberman isn’t waiting for CBO or anybody else to weigh in. He says he’s worried that the Medicare buy-in would be the first step towards a single-payer system–and that it would bust the budget. (At least, that’s his latest argument. As Steve Benen has noted, it’s changed a few times.) Ergo, it doesn’t have his support.

But Hot Air’s Ed Morrissey thinks Dems have been naive:

Why did this surprise anyone?  Last Wednesday, Lieberman warned that he couldn’t support a Medicare expansion.  A week ago, he appeared with Susan Collins for both of them to publicly oppose a government-run insurance option, reiterating the same position that he had publicly declared two days before Thanksgiving.

How can this be a “total flip-flop”?  It sounds as if Lieberman’s colleagues have wax stuck in their ears.

The American Spectator’s Philip Klein notes things have just gotten tougher for Majority Leader Reid: “Either Reid will have to pull a new compromise out of his hat like magic or get liberals to accept all of Nelson and Lieberman’s demands, or this thing is going to spill over into next year, and the whole effort may collapse altogether. But before you get too excited, just remember that the media was declaring health care legislation ‘inevitable’ last Tuesday, so we shouldn’t assume it’s doomed today. The story keeps changing.”