What caused this? If you ask me, it was 1) Single Issue voters, and 2) Voters that believe somehow they are teaching the republicans a lesson by effin themselves (by no-vote, or dem-vote).
You want to blame this on the voters???
The voters just weren't buying what the Republicans were selling. It's that simple.
And attitudes like yours are not going to woo a whole lot of voters back to the GOP either.