What struck me, however, was Drum's history:
As near as I can tell, there's a small but significant minority who are so enraged that they'd be perfectly happy to see his presidency destroyed as a kind of warning to future Democrats. It's extraordinarily self-destructive behavior — and typically liberal, unfortunately. Just ask LBJ, Jimmy Carter, and Bill Clinton. And then ask them whether liberal revolt, in the end, strengthened liberalism or conservatism.The thing is that these liberal revolts are hardly equivalent. Yes, liberals were clearly worse off with Nixon than they would have been with Humphrey (or for that matter another Johnson term), even, as it turned out, on the war. But the revolt against Johnson in 1965-1968 was hardly about warning future Democrats; it was, of course, about ending a horrible policy by the current Democratic administration. Even in hindsight, I think many -- most, probably -- of those who revolted against LBJ would claim that the risk of GOP victory was a necessary cost of doing the right thing in opposing the war (although I suspect that many, and probably most, of them would say that it was a mistake to punish Humphrey for LBJ's sins).
Carter? Liberals didn't really abandon Carter; they were never much with him to begin with. Unlike Clinton and Obama, who have both used conservative-sounding rhetoric (such as attacking wasteful government spending) but also supported important long-term liberal goals such as universal health care, Carter rarely placed any priority on liberal goals. For liberals, Carter was both inept at the job of being president and not a liberal. Moreover, there was someone available -- Ted Kennedy -- who was certainly a liberal and seemed well-equipped to handle the job. I think a lot of liberals who revolted against Carter would, in hindsight, still say that the increased risk of a Reagan victory was an acceptable risk given how much of a gain it would be to substitute Kennedy for Carter. Of course, many of those liberals would also claim that Kennedy, had he won the nomination, would have been a stronger candidate in November as well.
The point is that in neither of these cases were liberals (primarily) motivated by a desire to punish the president as a warning to future Dems that they should not stray.
Ah, but I do think that motivation shows up in the liberal (mostly labor) revolt against Clinton and the Democrats in 1994, and in the Dean/Hamsher revolt today. There is no intolerable policy that is clearly the president's choice (as Vietnam was), nor is there an obvious plausible liberal challenge (as Kennedy provided). Today's revolt, and the one in 1994, is just a frustrated "not left enough" reaction to political reality.
OK, now for speculation. I do wonder whether the 1993-1994 and 2009-2010 revolts were a learning effect. The theory would be that liberals learned from past betrayals (as they saw it) to be ever-vigilant, and eventually over-vigilant, to the possibility that Democrat presidents would betray them -- and learned that the proper response to that immanent betrayal is to turn against the president at the first sign of moderation. Conservatives, on the other hand, learned a very different lesson. Drum talks about conservative loyalty to G. W. Bush, but doesn't mention that conservatives were much more quick to criticize Ronald Reagan. True, those criticisms were generally directed towards James Baker, or Don Reagan, or Cap Weinberger ("Let Reagan be Reagan"), but the idea of Reagan as the perfect conservative president is very much a post-Reagan phenomenon. Conservatives who spent the 1980s criticizing Reagan learned that they were wrong; conservative presidents, apparently, should be given room by their allies to compromise with political reality.
Again, this is speculative. What I like about it as an explanation is that it doesn't depend on any inherent personality-type differences between liberals and conservatives, differences which in my view are often trotted out only when they fit something that people (usually liberals) want to believe. Is it true? I don't know.