Here’s one I pointed out a week ago or so,.
If Obama gets these taxes to go up (which he will as they are automatic) and for whatever reasons voters think the economy has improved in the next few years, for whatever reason (many things can happen), then Republicans are screwed.
This is what happened under Clinton.
But if the economy is still crap or gets worse than Republicans got an issue again.
I don't for-see anything happening like that in the near future.