I think this is simple, rather than simplistic:
- The people who are for Donald Trump, are for him. And almost nothing he can say or do, or that can be said or revealed about him, will undercut that support. The things that ordinarily would be considered “shocking” or “disqualifying” haven’t eroded belief among his base, and probably won’t.
- But there are not enough of these people to get 270 electoral votes for Trump. There were enough to give him an initial plurality in a huge GOP field, and to keep him coming out ahead as his GOP rivals foolishly attacked one another rather than concentrating on him. But in the general election his core support has remained below winning levels in virtually all honest polls. He has so far seemed to hit a ceiling at around 40% support—sobering in itself, but not enough.
- Therefore he needs new supporters—more women, more blacks and Latinos and Asians, more Muslims, more educated people, more of the young.
- Therefore2, the test of everything Trump does now—the debates, the “Miss Piggy” controversy, the taxes, everything—is whether it brings him anyone new. The question is not the one we mainly hear after debates or Trump flaps: how this affects his supporters. They already support him. The question is whether what he does and says brings in anyone undecided, or new.
My guess is that is has not.
The main point is: since Trump starts with not enough votes to win, the logical test to apply, in the 36 days that remain, is whether what he does with each speech, each answer in a debate, each tweet, each flux of the news cycle, expands his base. If it doesn’t, he has lost.