Calling Trump racist or a Nazi isn't effective. It's preaching to the choir. You don't convince his supporters, and you alienate the moderates that believe Trump is moderate like them.

This is deliberate. Trump deliberately made himself the motte-and-bailey candidate, so both moderates and extremists feel Trump is on their side. He's done that through double-messages and lying, so that the moderates came to believe that Trump was lying on his extreme proposals, and the extremists believed Trump was lying on his moderate proposals. Even his VP choice served that goal.

By calling Trump names, you're setting yourself up to be seen as unfairly strawmanning him, therefore reducing your credibility among the people you most want to convince. You're also setting yourself up to be seen as slyly using words as emotional hand-grenades ("nazi! bigot!") to shut down discourse, rather than actually believing these labels. Through that, you cede the moral high ground, not because you're manipulative, but because your target audience believes you are.

Hillary Clinton paid consultants millions to help her convince the public, and even that didn't work. Throwing around labels it hopeless. Regardless of whether you honestly believe those labels, they don't work anymore. Go on at your peril. I don't know what the solution is. Wider involvement in the political process, repeal of the Electoral College, and redistricting all seem like better ideas. And then, propose a positive vision, not just criticism of the other side.

Edit:

I'll be clearer: you're right. Do you want to be right, or do you want to win?