Why do I say this? Because we are in the middle of (and hopefully on the tail end of) a truly catastrophic recession. The economy will recover, although that may not happen for several years. It seems fair to say that the economy will not be roaring again any time soon, meaning that Obama will at best win by a squeaker. If it dips back into recession, he's toast. Most likely, it will end up just being a really competitive and interesting race on par with 2004.
The party occupying the White House when the economy does finally start booming will get the credit among the public for saving the country. It doesn't matter so much who was in power when the recession hit or whose policies helped or hurt the recovery. To a large extent, it's simply a matter of being in the Oval Office at the right time.
I've quoted Larry Bartels on this point before, but here it is again:
Considering America’s Depression-era politics in comparative perspective reinforces the impression that there may have been a good deal less real policy content to “throwing the bums out” than meets the eye. In the U.S.,voters replaced Republicans with Democrats and the economy improved. In Britain and Australia, voters replaced Labor governments with conservatives and the economy improved. In Sweden, voters replaced Conservatives with Liberals, then with Social Democrats, and the economy improved. In the Canadian agricultural province of Saskatchewan, voters replaced Conservatives with Socialists and the economy improved. In the adjacent agricultural province of Alberta, voters replaced a socialist party with a right-leaning funny-money party created from scratch by a charismatic radio preacher, and the economy improved. In Weimar Germany, where economic distress was deeper and longer-lasting, voters rejected all of the mainstream parties, the Nazis seized power, and the economy improved. In every case, the party that happened to be in power when the Depression eased dominated politics for a decade or more thereafter. It seems farfetched to imagine that all these contradictory shifts represented well-considered ideological conversions. A more parsimonious interpretation is that voters simply—and simple-mindedly—rewarded whoever happened to be in power when things got better.All this is to say that a handful of states in 2012 will likely determine Democratic or Republican dominance for the next decade or longer. And given the huge ideological gulf between the parties today, that means vastly different policies depending on the outcome.