Honestly this is the thing that kills Republicans. Yes, there is clearly and extreme right. And yes, there is clearly and extreme left. I don't think the majority of Americans identify with either.
The thing is...it's easier to delineate the extreme left from the Democratic majority than it is the extreme right from the GOP majority. I mean, having Obama v. Romney is a pretty good example. Obama basically does what he does and the extreme left is fairly quiet (even though he really isn't that liberal on a number of issues though a lot of the right refuse to admit this)...the "extreme right" though? Romney has to bow down at their feet. Boehner has no control. The Republicans need to get their own camp in order.