Nate Silver models the relationship between a President’s approval ratings and their re-election odds. This, of course, all about where President Obama stands for his chances of re-election in 2012.
Still, the approval rating at which an incumbent candidate goes from being an underdog to a favorite for re-election is somewhere in the high 40s.
The reason the threshold is probably slightly below 50 percent rather than right at 50 percent is that in any approval survey, some people (typically 5 to 10 percent) say they are undecided about the president’s performance. For instance, at this writing, Barack Obama’s Gallup approval rating is 49 percent but his disapproval rating is just 42 percent, a net margin of +7. If those were the figures on Election Day, he would be a favorite to win unless nearly everybody who was undecided about his performance cast their ballots against him, something that is possible in theory but usually doesn’t occur in practice.
If Obama can get the unemployment number down to about 6.5-7.5%, I don’t see how he loses in 2012. But if feels like everything hinges on that one statistic.