Romney cannot repudiate the birthers because he would be repudiating his own strategy in the process. All along he has tried to pander to the nutty GOP base just enough to get them to the polls, but not enough to alienate any sane or partially sane voters who might still vote for him. He has to have that crazy base, but he can’t win with them alone. It’s quite a balancing act, often forcing him to be in two positions at once. He is not a weasel because he is weak or incompetent. He is a weasel because that is how he intends to get elected.