The writer hosts MSNBC’s “The Rachel Maddow Show” and is a contributing columnist for The Post.

“Donald Trump is not a racist, but Donald Trump is not afraid. Don’t vote for a Cuban, vote for Donald Trump.” This is not the first white supremacist pro-Trump robocall by a group calling itself “American National Super PAC,” but it hits the same low notes as the last one. “We don’t need Muslims. We need smart, well-educated white people,” said the first call, which went out to Iowa and New Hampshire voters ahead of the presidential nominating contests in those states. The group’s pre-Super Tuesday call, which has reportedly gone out in Vermont and Minnesota, says, “The white race is dying out. . . . Few schools anymore have beautiful white children as the majority.” Both calls identify the person responsible for the message as a “farmer and white nationalist,” and both end the same way: “Vote Trump . . . This call is not authorized by Donald Trump.”

Trump has no affiliation with the white supremacists making these calls on his behalf, but he’s certainly got them all excited. The racist American Freedom Party is technically running its own candidate for president on a “Stop White Genocide” ticket, but its heart is clearly with Trump. A statement from the group announcing that first round of racist robocalls in Iowa called Trump “The Great White Hope.”

Before the first votes were cast this year, Trump’s candidacy was also being hailed and welcomed by the American Nazi Party, the KKK-affiliated “Knights Party,” the skinhead and neo-Nazi online forum “The Daily Stormer” and former KKK Grand Wizard David Duke.

[Joe Scarborough: Trump’s feigned ignorance about the KKK raises disturbing questions]

During appearances on network television Feb. 28, Republican presidential candidate Donald Trump repeatedly declined to refuse the endorsement of David Duke, a former grand wizard of the Ku Klux Klan. While Marco Rubio and Ted Cruz both took aim at Trump. (The Washington Post)

Duke started praising Trump on his radio show during the summer, saying that Trump’s campaign was doing “some incredibly great things,” but he stopped short of fully endorsing Trump’s candidacy. Now, Duke is overtly calling on his supporters to join the Trump campaign: “Voting against Donald Trump at this point, is really treason to your heritage. . . . I am telling you that it is your job now to get active. Get off your duff. Get off your rear-end that’s getting fatter and fatter for many of you every day on your chairs. When this show’s over, go out, call the Republican Party, but call Donald Trump’s headquarters, volunteer. They’re screaming for volunteers. Go in there, you’re gonna meet people who are going to have the same kind of mind-set that you have.”

Candidates cannot control who endorses them, and no one should hold candidates accountable for the views and actions of their supporters unless the candidates endorse them in turn. But that doesn’t mean the rest of us can’t notice who’s lining up behind whom.

While there is no evidence that Trump is actively courting the support of neo-Nazis and white supremacists, or that he welcomes it, that support also doesn’t come as a surprise after the campaign that he has run.

Since he has been running for president, Trump has twice retweeted a message from the account @WhiteGenocideTM. The name associated with the account is “Donald Trumpovitz,” and the user’s location is listed as “Jewmerica.” The avatar associated with the account — which Trump has twice sent to his own 6 million followers — includes the phrase, “The man who wants to be Hitler.”

In November, Trump also tweeted a graphic that showed wildly inaccurate statistics blaming African Americans for anti-white crime. The graphic originated from a Twitter account headed with a stylized swastika that is the symbol of a neo-Nazi group. The profane description of who the account belongs to includes the statement, “Should have listened to the Austrian chap with the little moustache.”

[George Will: The Trump albatross]

The Trump campaign, again, should not be conflated with its followers, but the candidate has not exactly gone out of his way to make clear to the white nationalists and neo-Nazis among us that their love is unrequited. After Duke started praising him last summer, Trump told interviewers who pressed him to repudiate the Klansman, “Sure, I would, if that would make you feel better.” Within the past few days, Trump said once that he disavowed Duke’s support, and then subsequently that he would not disavow it because he didn’t know who Duke was.

A man wearing a shirt saying "KKK endorses Trump" was thrown out of a rally for Republican presidential candidate Donald Trump in Oklahoma City, Okla."In the good old days they would rip him out of that seat so fast, but today everybody is so politically correct, our country is going to hell with being so politically correct," Trump said. (Reuters)

In 1991, Duke ran for office as the gubernatorial nominee of the Republican Party in Louisiana. Disgusted mainstream Republicans were beside themselves that a Klansman had become the party’s standard-bearer in that state. He was denounced by Republicans up to and including then-President George H.W. Bush.

That said, the Democratic Party’s candidate in that 1991 governor’s race was no prize either. Edwin Edwards had already served three terms as Louisiana governor, but he was flagrantly, even proudly, corrupt. Edwards ultimately went on to serve eight years in federal prison, but not before defeating Duke in a campaign that featured two of America’s all-time great political slogans: “Vote for the Crook. It’s Important” and “Vote for the Lizard, Not the Wizard.” The point is that Duke lost that race, even against an opponent like Edwards. Of course he lost. Characters like that are expected to lose in America, anywhere and everywhere.

Neo-Nazis, Klan members and white nationalists are a durable feature of the far-right fringe in U.S. politics. The constant reinvention and reintroduction of a character such as Duke over the years shows that our nation’s racist yahooism probably will never go away completely. It’s like a latent infection that becomes mildly symptomatic again every time we’re under too much stress.

What we’re not used to is it winning, and thereby getting a place in the spotlight at the center of mainstream, national politics.

[These new Trump poll numbers should terrify Republicans]

Maybe the Republican Party cracked the seal on this kind of thing in 2014, when it elevated Rep. Steve Scalise (R-La.) to the top tier of the House Republican leadership. Scalise, as a state legislator, once addressed a white supremacist convention of the European-American Unity and Rights Organization. He says he had no idea that it was a racist group, but a local reporter says he also told her at the time that Louisiana voters should think of him as “David Duke without the baggage.”

That’s a quote that the White House has frequently reiterated to the press corps since Republicans decided to elevate Scalise to the No. 3 job in the House.

The White House keeps bringing up the quote because it’s supposed to be a source of shame for Scalise and for the party in choosing him as a leader. That’s the usual interplay between the racist fringe and the mainstream political right: The overtly racist stuff is supposed to be a political loser and radioactive to mainstream Republicans. What is not usual is that same cast of racist characters and organizations feeling at home and well represented at the very apotheosis of Republican Party politics, in the campaign of the prohibitive front-runner for the party’s presidential nomination.

Again, a candidate cannot be held accountable for everything said and believed by his or her supporters. But once it’s clear that the candidate has both the attention and affection of the ugliest, most vile creatures in our political swamp, what he chooses to do about that is a leadership test not only for the candidate but also for the party of which he is becoming the standard-bearer. Now that the KKK and the white nationalists feel that the Republican Party has finally given them a candidate they can believe in, who will disabuse them of that notion? And how?