ANSWER: UNTIL AN ANTI-OBAMA COMES ALONG WHO DOESN'T SEEM LIKE VOLDEMORT

Amy Walter at ABC's Note asks:

How Much Longer Can Obama Defy Political Gravity?

Although President Obama's job approval rating of 48 percent (according to Pollster.com average) isn’t exactly stellar, it is remarkably high given the level of economic pessimism and despair among American electorate.

The economy is the most important issue for most Americans, yet few Americans feel very good about it and most don’t approve of the way President Obama's dealing with it.

... President Obama's job approval in the Quinnipiac Poll was 47 percent, a full nine points higher than the 38 percent who thought he was doing a good job on the economy. In the ABC /Washington Post poll, his overall approval rating was seven points higher than his approval rating on the economy. In the CBS/New York Times poll, the gap between his overall approval rating and his handling of the economy was 8 points.

Obama's job approval ratings defy political gravity. The only question now, is if they can do so for much longer....

The electorate embraces a lot of ideas promulgated by the meanest, nastiest Republicans, and the electorate voted in a lot of those nasty Republicans in 2010, but when it comes to embracing a head of government, the public wants someone with a bit of warmth and optimism. The public isn't ready to embrace the nasty SOBs of the Republican Party -- and I'd include Romney, Bachmann, and Perry in that category, no matter how much they all smile. Their message is still all about vindictiveness. It's too much.

Walter essentially answers her own question:

The greatest example of this cognitive dissonance was President George H.W. Bush. Even as he was riding high in job approval ratings thanks to the U. S. success in the Gulf War, voters were showing signs of restiveness about his handling of the economy.

In July of 1991, according to ABC News/Washington Post polling, Bush's approval rating was 70 percent, even as just 36 percent approved of the job he was doing on the economy and just 30 percent thought the country was headed in the right direction.

By June of 1992, the laws of political gravity and cognitive dissonance had taken their toll on Bush. At that point, only 23 percent of Americans approved of the job Bush was doing on the economy and his overall job approval rating was 35 percent.

Yup. That's when they had an alternative to cleave to -- after a dalliance with Ross Perot, they'd started to warm to Bill Clinton. He seemed competent and optimistic. So they felt free to let go of Poppy.

Romney (or, God help us, Perry or Bachmann) could wind up seeming like the happy warrior who'll lead us out of the wilderness eventually -- Nixon pulled it off in '68 by smiling a surprising amount and by promising to "bring us together." If we're desperate enough, and the status quo is unbearable enough, even an inadequate candidate can do that. But it may not happen. In any case, what's saving Obama's approval ratings in the interim is the apparent lack of an inspiring (i.e., non-snarling) alternative.