Lynn Vavreck finds that Obama's popularity has fallen but that he's not alone:
Obama still wins in [2012 presidential] contests between all three of the Republicans we asked about - Romney, Palin, and Gingrich. Against Romney, Obama’s loss in vote share from 2009 is seven points, from 48 to 41 percent so yes, Obama has lost votes this last year. But so, too, has everyone else. Romney’s share of the vote is down 10-points, from 42 to 32; and Gingrich’s dropped nine points, from 39 to 30. Palin loses the fewest votes, but she was starting from an already low baseline 35.2 in 2009 to 32.4 in 2010.
Voters like all the candidates less than they did a year ago, not just Barack Obama.
More context on his historically solid approval numbers and the previous parallels (Reagan and Clinton) to what seems about to happen next week here.