In a discussion on the Trinity, Trent Dougherty at Prosblogion rasies the question of whether President Bush is his own president. There's a sense in which Bush is the president of those who voted for him, i.e. they (at least at one point) identified with him as the person they wanted to be president. There's a broader sense in which he's the president of every U.S. citizen, i.e. he's the president who governs over them. That's the sense Trent has in mind. In that sense he is Ralph Nader's president as much as he is James Dobson's.
But is he his own president? Trent thinks yes, and I agree. Mike and Dale in the comments say no, and they offer two reasons. First, he can't pardon himself, which means he doesn't have that particular authority over himself. Second, he's not under his own authority, because as the top executive he's not under anyone's authority. I've adapted what follows from my comment on that post.