As I've said, he's more conservative/republican than McCain. The right has been grumbling for years about the current administration because of Bush's habits which most of us seem to think would continue under McCain.
Unfortunately when we're talking about the election it seems to me that it will be more decided on who is towards the center than at either extreme so this might make him more palatable for people who think that the (eventual) democratic candidate is too far to the left.