Gary Younge encapsulates the vicious cycle moderate Republicans find themselves in when it comes to the next Presidential election:
What is relatively new, however, is the level of logical dysfunction and hyperbole within the American right, trapped in a fetid media ecosystem where all the Kool-Aid has been spiked. In short, what you need to say and do to be credible within the Republican party essentially deprives you of credibility outside it. The Republicans seem to realise this, but like an obese glutton at an all-you-can-eat buffet, they just can't seem to help themselves.
Candidates like Sarah Palin and Michele Bachmann are wildly popular with the Republican base, but have absolutely zero chance of surviving on a national ticket. Palin essentially derailed the McCain Presidency as the center became horrified when it transpired she knew close to nothing about politics, and Bachmann is so laughably insane that even her admirers probably understand she would destroy any chances of a Republican White House.
The survivor of the GOP primary will most likely be a shameless but ultimately boring candidate viewed by the party funders as a safe pair of hands and a blank canvass upon which they can write a narrative to appeal to voters - most likely in the form of a Mitt Romney.
Romney has absolutely no problem reversing his core beliefs, and will say pretty much anything to get elected. He'll pass a health insurance mandate in his home state, then oppose it on a national level, be pro choice then pro life according to the stage of his career and come out in favor of President Obama's Afghan strategy in the morning, then criticize it in the afternoon. Romney was a successful business man and probably isn't a bad guy either, so can be marketed to both the business community and family-values conservatives. The problem is, he is so boring the GOP will have a hard time getting people excited enough to vote for him. Of course, they could solve the problem by having a serious internal confrontation to rid the party of the insane wing it has recently been taking orders from, but there is about as much chance of that as Rush Limbaugh apologizing for being a racist slob. It simply isn't going to happen.