If gas prices continue to stay down.
I think the economy will be a lot of it. There were also foreign policy crises, namely Russia, Iran and Iraq, two of which are reminiscent of the Carter administration. Obama, et al., have made the argument that if America is "respected" abroad, it will help. He has failed to realize that foreign countries act, correctly, in their own best interest.
I got a great premonition of doom last night watching those celebrations... we might have already seen the high point of his presidency.
Or maybe I'm just a miserable foreign git.
If, a year from now, Obama is still seen as the history making first black president, he has failed.