1) I think he wants to be popular.

2) Constitutional checks and balances.

3) My judgment is that he will not get captured by the State

4) Once we force the Republican Party to accept him ( we do this simply by electing him), then it will have more influence on "moderating" his "bad" behavior if only to preserve Party popularity.

5) Impeachment.

But I bet we'll be pleasantly surprised by how un-fascist he really is. For example, he has indicated that he is pro-choice, if only for the purposes of remaining popular.