Last night, MSNBC’s Keith Olbermann interviewed the filmmaker Michael Moore. Both of them are disgusted with the Democratic Party and its leadership. Now Olbermann and Moore inhabit a fantasy world in which Democrats are failing not because they passed ObamaCare but because they don’t have the courage to trumpet their support for it. Democrats, you see, are too spineless and too passive, not willing to thump their chests to celebrate their role in passing incredibly unpopular legislation.

This is what happens to dogmatic people when their grand ideological ambitions fail. It cannot be because of any defects in their ideology; the problem must rest with weak-willed politicians who aren’t aggressive enough to fight on behalf of their ideology. They don’t have the courage of their convictions.

This critique is of course ludicrous. But for President Obama, it highlights a serious threat: in the aftermath of the forthcoming midterm elections, where Democrats are going to suffer enormous losses, liberals will grow more angry, more disillusioned, and more disgusted with Obama and the Democratic Party establishment. They will blame the election losses on them, not on liberalism; and quicker than you can imagine, the defections will begin. And if Obama doesn’t begin to turn things around in 2011, he may well face a challenge from within his own party.

That might seem unthinkable now — but let’s see where things stand on November 3, when the recriminations get really ugly.

Failed presidencies elicit primary challenges. Just ask Jimmy Carter.

We’re clearly not at this point yet, of course, and a challenge to Obama is still more unlikely than not. And we haven’t seen a sitting president dislodged since LBJ. (Eugene McCarthy nearly defeated Johnson in the New Hampshire primary; Johnson withdrew shortly after that, and Hubert Humphrey went on to win the Democratic nomination.) But you can count on this: to protect liberalism, the left will jettison even Obama if it deems it necessary for The Cause. If Obama remains or becomes increasingly radioactive in 2011, liberals will seek to separate their movement from a deeply unpopular president. And the man who in the past has been so quick to throw others (like Jeremiah Wright) under the bus may find himself suffering a similar fate. The cruelest cut of all, of course, would be for this act to come courtesy of those who were once Obama’s more worshipful supporters.

That is part of the danger of having built a campaign on a cult of personality.