My job as a professor teaching European politics in the US revolves around explaining European political events to Americans. But as a dual citizen who grew up in Germany, I also spend much time during my frequent visits to Europe trying to help Europeans make sense of American politics.
Both of these efforts tend to involve highlighting that much of what we observe is driven not by fundamental differences between American and European values and preferences but by sets of political institutions that translate often similar inputs into vastly different outcomes.
I spent a good part of my summer in Europe for my research, and a big topic of conversation was Donald Trump. Europeans don't like him, but I have found them to be refreshingly self-reflective about his rise. They know they have no high horse to sit on when it comes to right-wing populist success; after all, many European countries have seen the rise of their own right-wing populist parties.
The exception is that at least some rush to emphasize that somebody like Trump would never become the candidate of a large center-right party in a European country. They see Trump's nomination as proof that what Europeans would consider to be radical right positions are "mainstream" in the United States.
Trump's success in becoming the candidate of a mainstream party demonstrates, however, that even if right-wing populism in the US and Europe share similar roots, how things play out is a function of differences in electoral systems and the number of parties on the one hand, and the strength of parties and how candidates for political office are selected on the other. These may not be the only factors that matter, but institutions decisively shape how attitudes and ideas are converted into outcomes.
Most European countries use some form of proportional representation (PR) to elect members of parliament, who then select the prime minister and cabinet from among themselves. Basically, proportional representation means that a party's share of the popular vote translates into about the same share of seats in the legislature.
For example, if a Green Party wins 7 percent of the popular vote, it will end up with roughly 7 percent of the seats in the legislature. This means that somebody like Trump would not have to become the candidate of a mainstream, center-right party in order to be electorally successful. He would have his own "Trump Party" and would not have to win the most votes to influence policy.
Under PR rules, even a relatively small vote share allows minor parties to gain seats in the legislature, and many far-right populists in Europe do not even aspire to actually win majorities and become part of the government (although some surely do). Their goal is to shape public discourse and pull other parties toward their own positions, and many are quite successful in achieving that objective.
In contrast, winner-takes-all systems, like we have in the US, make electoral success much more difficult to achieve. They distort the proportional translation of votes into seats and favor large parties capable of winning the most votes in given district.
Winning more votes than all other competitors is a high bar to clear for ideologically radical candidates or parties on either the far left or right and the reason we don't see Libertarian or Green Party candidates succeeding in the US very often. So for somebody like Trump to have the same impact as his right-wing populist counterparts in Europe, he has to wield influence through one of the two main parties.
While winner-takes-all elections like ours tend to produce two-party systems, as Maurice Duverger taught us long ago, countries that use PR typically feature more than two parties. Individual parties in such multi-party systems tend to cater to more cohesive groups of constituents and have an easier time navigating different issue dimensions.
For example, there may be two political parties that are both center-right on economic issues but differ from each other on social issues — an example of this would be Germany's Christian Democratic Union (CDU) and Free Democratic Party (FDP). These two parties can compete separately from, and with, one another under PR rules and still both be electorally successful.
A winner-takes-all system, in contrast, creates a need for a single center-right party capable of winning majorities; in this party, social conservatives and liberals would have to coexist awkwardly (sound familiar?). This has consequences for voters, who have fewer options from which to choose.
If, for example, the CDU selected a candidate for chancellor with too strong a social conservative profile, a more socially progressive voter could support the FDP. In the US, if somebody like Trump comes along, a traditional Republican voter can either hold his nose and support his party's candidate or choose to support Hilary Clinton either directly (by voting for her) or indirectly (by staying away from the ballot box). It is not surprising that many would (unhappily) choose the former.
It is this, rather than voters' enthusiastic support, that's key to explaining Trump polling well above the level of support enjoyed by European right-wing populists.
The two-party system also creates problems for party leaders, however, because maintaining broad coalitions of those with divergent interests is challenging. This is one reason the Republican Party has failed to prevent Trump from becoming the nominee.
But this failure also has to do with another key institutional feature of American politics: the primary. There are few equivalents of primary elections in Europe, and so it is generally the leaders of strong, hierarchical party organizations that pick candidates for office. As a result, there is little doubt that the leadership of a mainstream center-right party, in those dreaded "smoke-filled rooms," would have prevented a candidate like Trump from being nominated.
In 2016, most Europeans would probably have preferred a strong Republican party leadership stopping Trump's nomination. But in 2008 they fell in love with Barack Obama — the candidate who was the "outsider" in the matchup with Hilary Clinton, who was able to become the Democratic nominee because of the same selection process that now enabled Trump's rise. This is one important lesson of which most Europeans are likely unaware.
Another is that few Americans vote in primaries, and that those who do are not representative of the mainstream of the country or even of their own parties. And thus far, only 6.1 percent of the voting eligible population has actually cast a vote for Trump. This is far less support, I suspect, than Europeans think he enjoys.
Ironically, the selection process that made Trump's nomination possible is now making it more difficult for him to have broad popular appeal. This is a common challenge American presidential candidates face after having to satisfy an unrepresentative group of voters in primary contests, but it is particularly pronounced for Trump, for two reasons. First, much of what he has said, and how he said it, is difficult to leave behind. Second, he seems to have little interest in broadening his popular appeal and running a professional campaign. Relatedly, he is having a hard time stopping himself from making outrageous remarks that undermine his attempts to seem "presidential."
In the end, the institutional structure that allowed Trump to become the Republican nominee now undermines his chances of being electorally successful: He has to win the votes of a majority of voters, rather than Trump activists, without the backing of a strong, united party. And while European right-wing populist leaders can stick around without actually winning elections, an electoral loss would likely mean the end of Donald Trump, the politician, and it may seriously weaken the right-wing populist challenge in American politics looking forward.
Nils Ringe is an associate professor of political science, Jean Monnet chair, and director of the Center for European Studies and the Jean Monnet EU Center of Excellence at the University of Wisconsin Madison.