DW: You have defined populism as an ideology that separates society into two homogeneous and antagonistic groups, "the pure people" and "the corrupt elite" and which says that politics should be an expression of "the general will" of the people. How does Trumpism, for lack of a better word, fit that mould?

Cas Mudde: For most of his campaign it didn't really fit it, because - while he saw the elite as homogenous and corrupt and targeted both Republicans and Democrats - he didn't really say much about the people being pure. Most importantly he thought that politics should pretty much follow his will. Now in the last couple of months his campaign became much more populist and he actually presented himself more often as the voice of silent majority and as the voice of the people.

You argue that while comparisons between Donald Trump and European right-wing politicians are helpful, to be fully understood Trump must be seen as an American phenomenon. Why do you think that?   

One of the key things that made him attractive is this idea of him being a successful businessman. The US has a very strong tradition, particularly in the Republican Party, to believe that the president should be a kind of CEO of the United States who runs the country like a business. This is a very American view and not popular at all in Europe. I also think that the way he came up through the Republican Party and as a television personality are things that are much more pronounced and much more typical for the US than for Europe. In Europe almost all politicians that come through are representatives of a political party, often of a larger subculture. Trump is just an individual.

But Donald Trump has achieved what many right-wing politicians in Europe have not yet – to lead a country. What do you expect of a Trump presidency and what role will the Republican Party play in this?

It is very important to remember that Donald Trump was the radical-right leader of a non-radical-right party. You cannot really equate his support to someone like Marine Le Pen because a sizeable share of his voters, perhaps even a majority, just voted for the Republican Party and would maybe even have preferred to vote for a non-radical-right leader of the Republican Party, but didn't have that option.

What I expect of a Trump presidency is a very, very right-wing GOP government. If you look at his appointments, especially those that have cabinet rank and therefore need confirmation, they are mostly people who come from the very conservative, pro-business, anti-abortion wing and seem to have been facilitated by a group called Heritage Action, which is a very conservative group linked to the Heritage Foundation. And that part will be completely successful because that part is completely in line with the GOP, which holds, of course, both houses of Congress.

On top of that you have Trump and some of his more esoteric advisors like Bannon, Flynn and others. They will push for less common agenda points, particularly with regard to foreign policy where they will push for a different US policy position on Russia and also for some type of isolationism, as well as perhaps some larger socio-economic projects like the infrastructure plan. I think they will find themselves largely unsuccessful, because they will find a Congress that is completely unresponsive.

The key point is: How does the world respond to, let's put it mildly, a very unorthodox president? And that is the major threat of the Trump presidency – his unpredictability. 

That was my next question since you study populism and the extreme right. What can you tell us from your experience and research on how the world and the US should best deal with a President Trump? 

I don't think you really can learn any lessons because Trump is truly unique when compared to most other populist leaders in established democracies. He has no history and has no particular structure that ties him down. From that perspective he is really only kind of comparable to Silvio Berlusconi who also was a one-man-party businessman with no real political ties. But the big difference is Trump is the president of the US and Berlusconi was the prime minister of Italy.

The problem with Trump is every tweet that he sends is world news because of his position. And given that he sends erratic messages markets are going to respond, governments are going to respond and that is the big problem. The question will be: Will he learn and understand that whatever he does now has actual consequences in the real world? And I am skeptical about that if you look, for example, at his tweet storm from Sunday. It shows that he is still the same.

The lesson to learn is of course that everyone has to be vigilant, but also not to jump on everything. Because the other thing we learn is that he just spouts ideas and then moves on. Many things he said in the past are completely irrelevant today. So instead of panicking over every tweet it is crucial for the US and pretty much the rest of the world to take a step back and remember that this is Trump and wait to see what he does.   

In Austria's repeat presidential election next weekend a Green Party candidate will face a candidate of the right-wing Freedom Party. Do you expect a Trump effect? 

I don't expect a Trump effect, but I do expect Hofer, (the Freedom Party candidate, the ed.) to win. Europeans don't vote for far-right candidates simply because Americans voted for Trump. They vote for radical-right candidates for domestic reasons. And if you look at the polls, Hofer is up in most polls and he has been underpolled for the last year. So it seems logical to assume that he is going to win the presidency, but I don't think that Trump plays a major role in that.

Cas Mudde is an associate professor of political science at the University of Georgia with a focus on extremism and democracy. His most recent book "On Extremism and Democracy in Europe" was published earlier this year.   

The interview was conducted by Michael Knigge.