Here's why - they don't even believe their own positions. They want someone who is massively conservative and at the same time agrees with them on policy. The problem is the voters aren't nearly as conservative as they think they are. So they love the tough talking governor from Texas until they find out he wants to get rid of Social Security. They like that Michele Bachmann doesn't believe in global warming until they realize that she doesn't believe in it because she's bat-sh*t crazy.
If you choose ignorance as your party ideology why should it surprise you that you have completely ignorant party leaders? But it does, every single time. Watch, it'll happen again. This time with Herman Cain.
The voters are going to wake up a week from now and realize they're not sure they want someone leading the free world who doesn't know what Ubeki-beki-beki-stan is or what his own position on abortion is. They love his ignorance when it comes to science and basic economics, but they hate it when it shows how unqualified he is.
Well, you can't have it both ways. Someone who is remotely competent or sentient recognizes that 97% of the world's scientists are right about climate change (including even Koch funded scientists), that cutting deficits during tough economic times does not stimulate the economy and that firing state workers means we have less workers. But those are all against the stated position of Rush Limbaugh and Fox News. So, what is a Republican voter to do?
The answer is to fall in love with another conservative politician this week and find out he is a blithering idiot the next. Or worse yet, find out you don't really agree with any of those positions when they affect you (get your government hands off my Medicare!). That's the schizophrenia of the Republican electorate -- they keep switching leaders because they don't even believe their own positions.