If President Obama reaches a 50 percent approval rating by March, he'll be in good shape for re-election, a panel of pollsters and election observers said today.

Since the middle of July, the weekly average of Obama's approval rating has been between 40 and 43 percent, according to Gallup, which organized the panel for the media. The pollsters pointed to two recent presidents who didn't earn a second term to make the case for the importance of a 50-percent threshold: Just before Election Day, George H.W. Bush had a 34 percent rating, and Jimmy Carter was at 37 percent.

Victors, on the other hand, were comfortably above 50: Bill Clinton had 54 percent, and Ronald Reagan enjoyed 58 percent, for instance.

"If Obama's able to get in the 50s and stay there, then I think we pretty much know what's going to happen," Gallup managing editor Jeff Jones said, adding that if Obama can get to that point by March, he has a "good chance of being re-elected."

Historically, presidents' approval ratings haven't changed much during their re-election years. And at least before the parties' summer conventions, those ratings can fluctuate with less consequence, said Chris Wlezien, a political science professor at Temple University who has analyzed the accuracy of polls leading up to elections.

Other highlights from the Gallup briefing:

- Since the middle of October, Mitt Romney (along with most of the other Republican candidates) has seen a drop in the "positive intensity" voters have toward him, meaning that while they might favor him, they don't say they do strongly. Newt Gingrich, meanwhile, has soared from close to zero intensity at the beginning of August to 20 percent now, far above Romney's 9 percent.

- Gallup's "U.S. satisfaction" rating - how many Americans say they are satisfied with the way things are going - is at the lowest it has been since Carter was president, which is bad news for Obama. The number is at 14 percent. When Carter lost re-election, that number was 19 percent. Lydia Saad, a senior editor at Gallup, said Obama shouldn't feel more comfortable until that number is between 22 percent and 39 percent, the latter of which Clinton enjoyed for his re-election.

- David Rothschild, a research economist at Yahoo!, predicted that the change in the unemployment rate will be a better indicator of Obama's re-election prospects than the level itself on Election Day. He pointed to Reagan's re-election in 1984, when unemployment was at 7.4 percent, not great, but better than it was a year before, at 8.8 percent.