I’ll even wager that you yourself have friends you didn’t realize are Trump supporters. If you discover one, don’t shame them. Ask them, sincerely and openly, how they came to their decision. Because the ones who are least vocal about their support are probably the ones with the most compelling reasons for actually supporting him. These are the people who get what an asshole he is, yet believe they still need to vote for him. These are the people you should be engaging.
That’s how you change minds, you know. By connecting to them. Not by pounding them into submission.