There's a whole other dynamic in the equation which is corporatism that has infected our system that is the real culprit of the changes we've seen for some time but IMO... that is a right wing swing in which what was the left's representation in our government is now chasing historically what has been predominantly right-wing corporate money.
The Republican party has been getting pretty much most of what they want for a long time now. Now unions are almost non-existent by comparison to the past, taxes are incredibly low, social conservatives are pwning the dialogue and conversation so that we are refighting **** that was solved 40 years ago like birth control and abortion and the like.
Now, if you were to make a argument that you don't like the direction the country has taken, you can do so more honestly and accurately without trotting out "I don't like it therefore it is the left" cop out.
Meaning that there's less chance of the Republican party winning control of the Senate, and little chance of a conservative agenda getting much traction there.
Be careful what you wish for is the moral of the story.
Here is more information on the subject.
Jonathan Haidt on the moral roots of liberals and conservatives | Video on TED.com
There should be Instant Runoff Voting