Historian Richard Frankel, an expert on Nazi Germany, says history doesn’t have to repeat itself.

How is Donald Trump similar to, or different from, authoritarians and fascists such as Adolf Hitler? In what ways are "regular people" and Trump's "average" supporters implicated and responsible for his assault on democracy and campaign of cruelty? To what extend does the cruelty of Trump and his enablers toward immigrant children and other groups channel the evils of the Nazi regime? Do individuals working together have a chance to slow down Donald Trump and the Republican Party's assault on American democracy?

In an effort to answer these questions I recently spoke with Richard Frankel, a professor of history at the University of Louisiana at Lafayette and the author of "Bismarck’s Shadow: The Cult of Leadership and the Transformation of the German Right, 1898-1945." Frankel's work has also been featured in Newsweek and he frequently appears on the History News Network.

Donald Trump is waging a literal crusade against the American people and American democracy. But in these two years there have been few large national protests, economic strikes or other types of nationwide civil disobedience. It is all very disheartening. Are people just numb and tired? Have they surrendered?

There was the Women's March, which was just remarkable and incredibly inspiring. But overall I sense that with one thing constantly following the other, how do people decide what to protest? Of course at certain moments in our history protests are more common than at other times but getting out in the streets is not as big a part of our political culture as it is elsewhere.

With Trump we also keep coming back to the question, "How is this happening? What can we do about it?"

Looking at Trump and his supporters' authoritarian views and apparent disdain for normal politics and democracy, it does not seem that this situation will end well. 

I do think there's certainly a very strong possibility that it's not going to end well -- and that's from the perspective of a German historian. And as a historian, my natural tendency is to always try to stop people from invoking Hitler. In most cases it was not appropriate to make such a comparison. But now, with Trump, my resistance and that of other historians to making that comparison is being overcome.

But there is an important qualifier: History doesn't have to repeat. It doesn't have to look exactly like what happened before. It won't. But if we wait for Trump and this moment to fully become like Hitler and the Nazis, and that is the point at which you start to act, then it is already too late. The unfortunate aspect is that if you set the bar so high in terms of outrage and horror then people all too often let things continue when they could have been stopped earlier. Once it gets to that point it's way too late.

Where I see things going right now with Donald Trump is that if he is not stopped the result will be some form of authoritarian, racially exclusionary democracy. My focus is much less on a particular system, whether he's a fascist or not. It's much more the question of exclusion. Trump and his allies are trying to create a kind of white, Christian, male-dominated national community for their followers. He's drawing the boundaries around that community and excluding all those groups that don't fit in, whether it's the handicapped, immigrants, Muslims, Jews or other groups. Those Americans and others who are not part of Trump's imagined community will be second-class citizens and will have their rights restricted.