 He could. The only person I think really would have the possibility of forcing him out would be Jill, who does not at all seem to want that to happen. And even then, in theory, he could stay in. Now, if your wife's on your case, most guys fold. But in theory, he's the president of the freaking United States, man. It doesn't matter how incoherent he is. If you want a 25th Amendment him, you can.