The Democrats run Lieberman/Obama. IMHO, Obama is their perfect VP, it's just that he doesn't want to run with Hillary. What man would?
But I don't see any Republican with the nerve to tackle Hillary head-on, the way Barak Hussein and his old lady are doing.
As to any Republican taking on Hillary, Karl Rove has been assigned that task. And when it is time, the candidates will start hitting her altogether, if she ever starts making pronouncements worthy of respponse. So far Hillary has just been a horrible boor, and no one is terribly interested in what she has to say.