Dana Milbank: Trump has done the impossible. He has united the Democrats.

U.S. Rep. Alexandria Ocasio-Cortez, D-N.Y., speaks as, from left, Rep. Rashida Tlaib, D-Mich., Rep. Ilhan Omar, D-Minn., and Rep. Ayanna Pressley, D-Mass., listen during a news conference at the Capitol in Washington, Monday, July 15, 2019. President Donald Trump on Monday intensified his incendiary comments about the four Democratic congresswomen of color, urging them to get out if they don't like things going on in America. They fired back at what they called his "xenophobic bigoted remarks" and said it was time for impeachment. (AP Photo/J. Scott Applewhite)

Washington • President Trump, bless him, has once again achieved the impossible: He has unified the Democrats.

The fractious opposition party had been holding one of its regular Festivals of Gratuitous Self-Injury over the past few weeks on the matter of race. Sen. Kamala Harris (Calif.) and other Democratic presidential candidates had attacked the “hurtful” actions of front-runner Joe Biden from decades ago in opposing busing and in working with segregationist senators. Rep. Alexandria Ocasio-Cortez (N.Y.) split Democrats by accusing Speaker Nancy Pelosi (Calif.) of the “explicit singling out of newly elected women of color.”

Now, Trump has come to the Democrats’ rescue by reminding them, and all the world, what racism really looks like. On Sunday, he attacked four nonwhite Democratic congresswomen — Ocasio-Cortez, Ayanna Pressley (Mass.), Ilhan Omar (Minn.) and Rashida Tlaib (Mich.) — by saying they “originally came from countries whose governments are a complete and total catastrophe” and proposing that they “go back” to the “broken and crime infested places from which they came.”

Thus, Trump would have these lawmakers "go back" to Ohio (in Pressley's case), New York (Ocasio-Cortez's birthplace) and Michigan (Tlaib's). Omar, who emigrated from Somalia as a child, grew up in Minnesota. Rather than back down from this notion that nonwhites are not American, Trump broadened his attack on the four on Monday, saying they "hate our country" and proposing they "apologize to our country" and to him.

And Democrats were bickering over Biden's relationship with James Eastland in 1973?

Democrats' differences are trivial, or should be, as they spend the next 16 months preparing for an election that will either affirm America as a multicultural society or define it as a redoubt of white nationalism. Trump's racist words, clearly aimed at firing up his most ardent supporters, will, as in 2018, bring out his opponents in even greater numbers — as long as Democrats can move beyond their own squabbles.

It has been nearly four years since I wrote a column that began: "Let's not mince words: Donald Trump is a bigot and a racist." This was controversial at the time, even though we had already seen Trump's behavior with the Central Park Five and the birther movement, his routine attacks against Muslims and his branding of Mexican immigrants as rapists and killers.

But the past four years should have extinguished any doubt about his racism: his defense of “very fine people” at the neo-Nazi march in Charlottesville, his attacks against black NFL players, his denunciation of “s---hole countries” in Africa and elsewhere, his claim that Haitian immigrants “all have AIDS,” his mockery of “Pocahontas” and the Trail of Tears. During just the past few weeks, Trump threatened, in defiance of the Supreme Court, to change the census in a way that the administration’s own expert said would disadvantage nonwhite Hispanics. As then-Speaker Paul Ryan said when Trump declared that a Mexican American judge couldn’t be impartial because of his ethnicity, this is “textbook” racism.

Yet even now, there remains some squeamishness about calling Trump what he is. The New York Times said Trump has fanned "the flames of a racial fire." CNN called his words "racially charged." The Washington Post said he "used a trope broadly viewed as racist."

It's long past time to stop pretending. Studies before and after the 2016 election showed that racial animus was the primary motivation of Trump voters, even more than economic concern. Certainly, many Trump voters were motivated by the hope of tax cuts and of Supreme Court picks. But with each of Trump's successive racist outbursts, it should become more difficult for at least some of these Republicans to stomach the white nationalism Trump promotes.

This is surely why Republican officeholders have been almost universally silent about Trump's latest ugliness, and GOP leaders have been shamefully mute. Of the few to speak, Rep. Will Hurd (Tex.), the lone black Republican in the House, denounced Trump's "racist and xenophobic" words. Rep. Justin Amash (Mich.), an independent who recently quit the GOP, likely gave voice to his cowardly colleagues' unspoken sentiments when he called Trump's words "racist and disgusting."

Trump's naked bigotry inspired House Democrats on Monday to set aside the skirmish between Pelosi's leadership team and Ocasio-Cortez's "Squad." Instead, they prepared a House resolution denouncing Trump's words.

That's a start. But for the next 16 months, Democrats must remember that their own differences are relatively insignificant. The latest racism is a new low for Trump, but worse will undoubtedly come. For Trump, there will be no bottom — unless and until voters tell him to go back to the place from which he came.

Dana Milbank | The Washington Post

Follow Dana Milbank on Twitter, @Milbank.