The president of the United States just interrupted an immigration meeting in the White House to tell a group of presumably surprised lawmakers that the United States was “having all these people from shithole countries come here.”

He suggested, per the Washington Post, that the US should stop admitting immigrants from Haiti and El Salvador and instead bring in more people from Norway, whose prime minister met with Trump on Wednesday.

The sheer racism of the comments would be shocking coming from any other president. The heartbreaking, and terrifying, thing is that it’s not the least bit surprising coming from Donald Trump.

This is a man who launched his political career by pushing a conspiracy theory that the first black president was not actually born in America. This is a candidate who rocketed to the top of the GOP primary polls by calling Mexicans rapists. This is a president who has repeatedly attempted to act on his campaign pledge to ban Muslims from entering the United States, who has said that Haitian immigrants “all have AIDS” and that Nigerians live in “huts.”

It’s not just that Trump has consistently and unambiguously expressed beliefs like this — though he has. It’s that his willingness to say these things, out loud, is the core of his political appeal to his vaunted base. Trump won the GOP primary and the presidency not in spite of his xenophobia and racism, but because of them.

Put even more bluntly, his talk about “shithole countries” is a perfect distillation of Trumpism.

“Trumpism” is just the politics of white grievance

Political scientists who study race and immigration find that they have played a central role in the transformation of American politics. Democratic support for civil rights legislation and mass Latino immigration led to a sea change in American voting, wherein white voters who feel high levels of racial resentment shifted en masse into the Republican Party.

Lee Drutman, a senior fellow at New America, charted Republican and Democratic feelings of “warmness” toward black people (rated on a 1-100 scale). He found a consistent gap, one that has widened considerably in recent years:

Drutman’s results were similar for feelings toward Hispanics:

This meant that a candidate like Trump, someone who was willing to openly disparage minority groups and immigrants, had an opening in the Republican primary. Someone who could mobilize these voters by telling them what they really wanted to hear would be able to command their votes.

That’s exactly what happened. Michael Tesler, a professor at the University of California Irvine, took a look at racial resentment scores among Republican primary voters in the past three GOP primaries. In 2008 and 2012, Tesler found, Republican voters who scored higher were less likely to vote for the eventual winner. The more racial bias you harbored, the less likely you were to vote for Mitt Romney or John McCain.

With Trump, the opposite was the case. The more a person saw black people as lazy and undeserving, the more likely they were to vote for the self-proclaimed billionaire.

You might think that looking back to the primary is old news — but really, it isn’t. Trump’s “base,” his most hardcore supporters, are the people who helped make him the Republican standard-bearer. Primary data is some of the best evidence we have about the nature of Trump’s support — and it suggests that xenophobia and racism were the defining part of Trump’s support.

It’s also borne out by research on the general election. One such paper, by political scientists Brian Schaffner, Matthew MacWilliams, and Tatishe Nteta, found that racism was an incredibly powerful predictor of a person’s likelihood of voting Trump — outpacing economic anxiety and even sexism.

My colleague German Lopez has a good piece running down more research on a similar line. His conclusion is that “the evidence that Trump’s rise was driven by racism and racial resentment is fairly stacked.”

To understand Trumpism, look to Europe

Trumpism’s closest analogue in other countries is European far-right parties, which have made immigration the core of their political appeal and have found political success. Statistical studies find, consistently and unambiguously, that parties like France’s National Front and Germany’s Alternatives for Deutschland (AfD) derive the bulk of their support by marshaling anti-immigrant sentiment.

This sentiment is created not by a feeling of economic threat, fear that Europeans would have to compete for their jobs, but by a sensation of cultural threat — a sense that people from Muslim countries, places that Trump might term “shitholes,” were alien to Europe and not welcome.

A group of Belgian researchers examined support for a far-right party in their country, Vlaams Blok, at the municipal and national levels. Instead of just looking at the impact of the presence of “immigrants” in a particular area, they looked at different types of immigrants.

Specifically, they separated out immigrants from Turkey and Africa’s Muslim-majority Maghreb region, which includes such countries as Morocco, Tunisia, and Algeria. They found that the presence of Muslim immigrants correlated well with increased support for Vlaams Blok, but the presence of non-Muslim immigrant populations didn’t.

”It is not so much the presence of foreigners, but rather the fear of the Islamic way of living that leads to extreme right voting,” they write.

The comparison to the European far right parties, which are functionally single-issue parties focusing on immigration, is vital to helping us understand Trumpism. These parties took advantage of European cultural anxiety, of fears of difference, to build entirely new political movements that took Europe by storm.

Trump did much the same thing in the United States. His policy stances on other issues — taxes, health care, North Korea, Syria — shift by the day, often based on whoever he talked to last. He can’t seem to make up his mind on a Trump view of the economy, at least not one he’s consistently acted on, or on a Trump doctrine in foreign policy.

He’s been consistent on only one thing throughout his campaign and in his presidency: mobilizing cultural resentment. From his fight with “Mexican” Judge Gonzalo Curiel (who was born in Indiana) to his battle with the NFL over black players kneeling to protest racism to his willingness to whitewash the neo-Nazis who marched in Charlottesville, Virginia, last August, divisive racial and cultural politics have been at the center of his appeal. Polling suggests that Trump’s core supporters back him on this stuff to the hilt.

Trumpism is not complicated. It is the weaponization of anti-immigrant and anti-black sentiment to further Donald Trump’s political ambitions. The “shithole” comment is not an exception. It’s the rule.