People make a lot out of the fact that many GOP presidential hopefuls have had divorces and otherwise messy marital histories, but I can't see this being a huge factor in keeping anybody from getting the nomination. The target audience for attacks on someone's marital history usually isn't primary-voting party activists, whose ideological commitments run too deep for biography to easily sway them. Tell them about pedophilia or an illegitimate black child, and you'll do real damage, but mere divorce is far from a deal-breaker.
The target audience for that sort of thing is swing voters, whose ideological commitments aren't deep enough to tie them to one party or another, and who like their political information on the People Magazine level anyway. They can be won over by giving flattering or unflattering biographical pictures of candidates, and the Republicans have enough religion hustlers to do that work well. To put this in the coarsest terms, Republican concern for 'family values' in terms of a candidate's personal relations is a sham, and there's no reason to expect that it'll play a big role in their nomination process. But in a general election, the cost of being a serial divorcer -- or worse, a serial divorcer of ailing women -- comes due. (Especially if your opponent is being a caring husband to his cancer-stricken wife.)
