As Rod notes, Ross Douthat maintains that Romney could still recover and win. If he did so, it would involve an unusual late shift in the race towards the challenger. On Monday, Nate Silver reviewed late September polling from 1936 to 2008 and compared it with the final results, and this was one of his conclusions:

There has not been any tendency, at least at this stage of the race, for the contest to break toward the challenging candidate.

Instead, it’s actually the incumbent-party candidate who has gained ground on average since 1936 [bold mine-DL]. On average, the incumbent candidate added 4.6 percentage points between the late September polls and his actual Election Day result, whereas the challenger gained 2.5 percentage points.

Silver went on to acknowledge that the challenger has gained more on average than the incumbent-party candidate in elections since 1996, but that has not been the pattern in most presidential elections over the last three-quarters of a century. The expectation that a large enough majority of late-deciding voters will break in favor of Romney to allow him to win seems to be based on a faulty assumption. Romney seems particularly unsuited to pulling off the sort of comeback that his supporters want to see, but in fairness to Romney it would be a remarkable and unusual thing for any trailing challenger to do at this point. It doesn’t make it any easier that Romney is the least-liked major party nominee in decades.

Setting aside the weaknesses of the challenger this year, it is useful to remember that the re-election of an incumbent president is far more common than defeat. Incumbent presidents have lost three times since 1976, so we may be inclined to think it is not so unusual, but that’s wrong. Incumbent presidents have won thirteen elections since the start of the twentieth century, and they have lost five. One of the burdens Romney has been laboring under is one of his own party’s making, which is their belief that the incumbent wasn’t the favorite to win all along. As Jonathan Bernstein points out, Obama should have been considered the “mild favorite” in the race.

If Obama was always the favorite to win, Romney might have lost even if he hadn’t made so many mistakes. Because Romney’s supporters imagine that this was an election they couldn’t lose, or one that they could lose only with great difficulty, they see him blowing what Laura Ingraham has called a “gimme election.” Many of Romney’s supporters have overestimated chances of Republican victory from the beginning, which leads them to exaggerate both the extent of Romney’s failure and the possibility for a late comeback. Romney is undoubtedly a bad candidate, but he might not have been able to win even if he weren’t. Because he is such a bad candidate, he isn’t likely to be able to pull off a comeback in a race against an incumbent president.