Of all these arguments, the only two you are likely to hear ad nauseam are: too much social conservatism and too much war.
Why? Because that's the view of the liberal establishment that for 40 years has been arguing that if only conservatives were more liberal they'd be more successful, even as the conservative movement has been the most successful political enterprise of the last half-century.
Philosophically, reasonable people may differ about whether there's been too much social conservatism, but politically, this is idiotic. As Ramesh Ponnuru notes in the National Review, Christian conservatives give the GOP as many votes as labor and blacks combined give to the Democrats. It's to the Republicans' electoral advantage to take positions that shock the conscience of Rosie O'Donnell.
It's also true that the Iraq war is unpopular; that's because it's not going swimmingly. If it were otherwise, Iraq would be a political boon to the GOP. Now, you might say, "Yeah, and except for the brief unpleasantness, Mrs. Lincoln had a wonderful time at the theater." But it is not the conservative position to botch wars. And contrary to the slanderous codswallop you've heard for the last year, conservative principles do not require flooding New Orleans. While we're on this point, corruption and cronyism aren't core planks in the conservative platform either. Rep. Don Sherwood (R-Pa.) lost his seat because of an alleged personal scandal, but I can assure you there's nothing in the works of Edmund Burke that says a good conservative should try to strangle his mistress.
In other words, just as Democrats insisted, the GOP's drubbing had more to do with competence and scandal than program and ideology.
Indeed, if the conservative base hadn't been disgusted with Republican management, and if so many Democrats hadn't run as social conservatives, the GOP might have done just fine in this election.
Republicans lost because they behaved like self-indulgent politicians, not purists. Conservatives care a lot about ideas, so that's where we'll try to assign blame. But the ideologues aren't to blame. The Republicans are.