When you have a President in his 6th year with declining approval ratings and people don't feel good about the way things are going. The result simply isn't going to be good for the incumbent party.
I mean just look at GWB for that example,
I find it very interesting how the Left in general is blaming everything else except the President's unpopularity and their inflexible campaign strategy for what happened on election night.
It's funny how history somehow manages to repeat itself, huh? But then again, it can't be fundamentals or anything like that, right? Of course not. /sarcasm