From a strategy perspective, it is the only card he has left to play.
Right now it is not about winning for McCain, it is about not losing by a landslide, so these negative attacks will fire up the base and make sure he does not lose by enough for the current GOP power brokers to be challenged by any party activists.
Given the context, Sarah Palin’s attack yesterday on Barack Obama’s patriotism and his “ties” to former Weather Underground ringleader William Ayers works.
Of course this turn is bad for the country and bad for our democracy, but McCain has shown time and time again that he does not give a crap about the country. He also knows that there will not be any blowback from so-called Republican moderates like Mike Castle, or Dave Burris for going negative – so there is no real downside for him.
If I’m a republican right now, I’m thinking McCain made the right call for once.