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President Trump tweets with such frenzy and frequency that we have become almost inured to his rhetorical excesses. But there are times when you have to pay attention.

Over the weekend, Trump tweeted out a widely condemned attack on four Democratic congresswomen: Reps. Alexandria Ocasio-Cortez (N.Y.), Ilhan Omar (Minn.), Ayanna Pressley (Mass.) and Rashida Tlaib (Mich.). All four are freshmen lawmakers, women of color and outspoken, left-wing voices in the Democratic Party; only one, Omar, was born outside of the United States.

Yet Trump urged them to “go back” to the “crime infested places from which they came” and stated they all “originally came from countries whose governments are a complete and total catastrophe.” The venom behind the tweets was unmistakable: Here was Trump openly questioning four minority women’s place in America. It was in keeping with the president’s lengthy history of white nationalism, from his “birtherist” campaign against America’s first black president, to his slurs at a Mexican American judge, to his preference for migrants from Norway over “shithole countries,” to his blanket attacks on Muslims, to his defense of white supremacist protesters, to his administration’s daily demonization of immigrants and minority communities.

Trump was soon on the receiving end of an outpouring of disgust from Democratic politicians as well as European leaders. In the United States and elsewhere, there’s little neutral about telling someone to “go back” to where they came from.

"I’ve heard it from racists and fascists. Never from a mainstream politician,” said London Mayor Sadiq Khan. “Here you have the president of the U.S.A. using that same sort of language.”

But such is the vortex of polarization swirling around the White House that Trump only felt more emboldened the following day. When asked by reporters whether he had any regrets about his remarks being broadly perceived as racist, he doubled down, branding the lawmakers as “communist,” falsely suggesting that Omar had celebrated terrorist group al-Qaeda and warning that all four somehow represented a threat to Israel.

“It doesn’t concern me because many people agree with me,” Trump said. “And all I’m saying — they want to leave, they can leave.”

Some critics pointed to the blatant hypocrisy of Trump — who, in his tumultuous political life, has lambasted American civic institutions, cities, war heroes and the concept of American “exceptionalism” while also praising anti-American dictators — suggesting that opponents unhappy with America’s present state should leave. Others tut-tutted about the president mistakenly targeting women born in the United States.

To the Atlantic’s Adam Serwer, a trenchant critic of Trump’s racial politics, that last objection misses the point. “When Trump told these women to ‘go back,’ he was not making a factual claim about where they were born,” wrote Serwer. “He was stating his ideological belief that American citizenship is fundamentally racial, that only white people can truly be citizens, and that people of color, immigrants in particular, are only conditionally American. This is a cornerstone of white nationalism, and one of the president’s few closely held ideological beliefs. It is a moral conviction, not a statement of fact.”

And it’s not just his moral conviction. Trump is probably right that “many people” agree with his attacks on the left-wing lawmakers; his Twitter screeds stir up a segment of his Republican base and inflame the country’s right-wing media ecosystem. Ahead of the 2020 election, he has already decided that his campaign pitch will be the same as 2016 — that his opponents are betrayers of the nation, enemies of “real” Americans, enablers of all sorts of alien threats. And the last thing he’ll do is acknowledge that there is anything racist about what he says.

“This denial is more than just an effort to minimize the political damage such racist displays might do among swing voters,” wrote Washington Post columnist Greg Sargent. “The explicit idea here is that Trump is free to engage in public racism without it being called out for what it really is, that is, with no apology or capitulation to those who label it as such.”

Trump saw a white nationalist seam in Republican politics and pulled at it to achieve power. He kept tugging and tugging and has dragged in his direction the entirety of the Republican Party — a party, as New York Times columnist Jamelle Bouie wrote, “that elevates its narrow, shrinking base as the only authentic America and would rather restrict the electorate than persuade new voters.” Only a smattering of prominent GOP politicians came out to denounce the president’s remarks; many stayed silent or echoed Trump’s jabs at their Democratic opponents.

It was evidence, once more, of what some analysts see as Trump’s steady assault on norms in American political life — in this instance, the supposedly entrenched belief in the equality of all American citizens, no matter their ethnicity or place of birth.

“But a norm that was built up through speech, persuasion, and belief can be undermined the same way,” observed political philosopher Jacob Levy in a 2018 essay. “Trump’s own racism, his embrace of white nationalist discourse, and his encouragement of the alt-right over the past two years have, through words, made a start on that transformation.”

Levy concluded that “Trump’s stump speeches and unhinged tweets . . . are changing what Republican voters think it means to be a Republican.”

What it means to be Republican now is to be firmly on the far right of Western politics. When set against many of their Western European counterparts, American political parties have always skewed a bit to the right. But Trump has accelerated the steady morphing of the once big tent conservative faction into a vehicle for primal nativist rage and resentment, in some instances in line with Europe’s ultranationalist, far-right parties.

A study published last month in the New York Times attempted to map where the Democrats and Republicans sit across a spectrum of Western parties through an analysis of individual party platforms. It placed Trump’s Republicans to the right of a number of parties with an explicit history of neo-fascism; the Democrats, meanwhile, are seen as largely centrist.

That asymmetry is a defining and oft-ignored aspect of American politics, where platitudes over the need for bipartisanship and consensus governance still remain Washington mantra. Through his racist demagoguery, though, Trump is doing a good job bringing the new reality into focus.

“The difference is that in Europe, far-right populist parties are often an alternative to the mainstream,” noted the Times. “In the United States, the Republican Party is the mainstream.”

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