The combination of out of control spending and the GOP's lack of action on illegal immigration had a depressing effect on the base. The Iraq War is also not as supported among the base as it was 2 years ago.
The illegal immigration issue was the tipping point that finally convinced many republican voters to sit this one out. Since both the democrats and the republican parties have the same policy on illegal immigration, of course it isn't going to show up on any exit polling.
Many of us warned the GOP months ago and especially this spring during the illegal immigrant marches that if something substantial wasn't done before the election that the base would be depressed and the party would take a beating.
And now look at Congress, compared to what it was yesterday. Brilliant!
If ever an election wasn't about the base, this is it. With GOTV and the rest the base got out. This comes down to the middle. We need to focus on the big tent as well as our core issues.