What, exactly, is the Republicans' problem? President Obama looks highly vulnerable as he begins his campaign for re-election. His job ratings, even after the elimination of Osama bin Laden, are only middling--around 50%, which is the threshold for re-election. Last year's midterm was catastrophic for Democrats. The excitement factor, which drew huge Democratic turnout in 2008, is not there anymore. And the economy is worse than it was when Obama took office.