The problem with your idea is that is has a very short term focus. Would there ever have been a President Reagan if not for Goldwater? Maybe not.
Sticking to your principles sometimes make sense; but you may not be able to be determine what the long term consequences of doing so will be.
Leadership does not always mean winning.
think you may have missed the point. If Bush doesn't win, he can't lead, or not lead. the entire point is moot. If you're talking about long term strategy, it might be better if he lost. After four years of Kerry, Hitlery might not have the chance of a snowball in Hell. On the other hand, who knows the future? Sorry to always be quoting books, but "Of Mice and Men" comes to mind.