Like Robert Heinlein said, in words not exactly like these; the real problem is that we never get a chance to elect people who aren't lusting after power. It would be better to put someone in power who has to be dragged there kicking and screaming and who would just do the job and want nothing more out of it than to get out at the end of term

Actually, that somewhat describes Harry Truman. Initially he didn't want the position - and while I don't agree with everything he did, he was, in several ways, a very effective leader.