If nothing else, a presidential campaign tests a candidate's ability to think strategically and tactically and to manage a very complex organization. We have three plausible candidates remaining--Obama, Clinton and John McCain--and Obama has proved himself the best executive by far. Both the Clinton and the McCain campaigns have gone broke at crucial moments. So much for fiscal responsibility.While it's certainly true that John McCain allowed his campaign to be bankrupted, it's also true that he righted its course -- and essentially performed a miraculous "turn-around."
Since there is no doubt that in four years in the White House, problems will undoubtedly occur, it seems to me that the ability to pick oneself up and turn around a bad situation is one of the best skill-sets a future president could possess.