The republicans aren't the only ones who don't want to make it an issue. Obama said in a speech this weekend that Palin's family is off limits, and that if he finds out anyone in his campaign had anything to do with this story hitting the news they would be fired.
I read an article this morning about how lots of evangelicals are rallying behind Palin for "the fact that this family lives its pro-life values". Perhaps this was part of the plan for McCain to win back some of the conservative base that doesn't think he is conservative enough.