Nate Silver connects Obama's approval ratings slide to various events:
I'm not going to be able to give you any one incredibly satisfying answer here. The most basic reason for the decline in Obama's numbers, almost certainly, is that people's expectations for what he ought to have been able to accomplish on the economy have accelerated faster than his ability to do so. But beyond
that, things are a little murky.
The periods that represent the steepest declines in Obama's approval ratings are only loosely related to the periods that provided the most disappointing economic news. Meanwhile, while I'm sure that the health care bill hasn't helped Obama any, the trajectory of that debate isn't a great fit for the trajectory of his approval numbers. Finally, factors like the nomination of Sonia Sotomayor and the seating of Al Franken may not have been terribly impactful unto themselves, but may have given rise to unhelpful narratives for Obama and the Democrats that contributed to their problems.
The Dish 