That will only happen if the Federal Government refuses to bail out the states. I expect that California will be the test case. Granted there already has been one refusal, but to make it official, there has to be more refusals.
I see that happening in 7 - 12 months once the bailout libs (of both parties) are ousted. But if Greece falls completely which is more likely to happen BEFORE that, it will happen before the election.
If the slide begins before November, this election's going to be an orgy of panic and bloodbath for incumbents. Even more so and even the few good ones are going to fall.