Really? Considering their opposition, I'd say they could run Bozo the Clown and win.
If you think you beat an incumbent President by being "Not Him" you should ask Kerry or Dole how that worked out for them.
You can get away with being the "Not the Incumbent" candidate farther down ticket, but up ticket people tend to vote for the incumbent candidate unless you really make a case for why you're the better man. Most of the GOP field seems to have forgotten this, which is downright scary. Here in the primary phase of the game you set yourself apart based on your ideas, and right now you have a whole group of folks for whom their only publicly stated policy initiative is "I'm not Obama."
Most incumbents haven't screwed the pooch nearly as bad as this one has either. Things change. Shit happens.