Once upon a time, I thought the repudiation of white supremacists was the easiest layup in U.S. politics. Not for the Trump campaign.

Asked recently whether he considered former KKK leader David Duke deplorable, Republican vice-presidential nominee Mike Pence said he was “not in the name-calling business.” Earlier this year, Donald Trump was posed a similar question and claimed, incredibly and repeatedly, “I don’t know anything about David Duke.” In a particularly revealing campaign moment, Trump was asked to repudiate the anti-Semitic death threats made by some of his followers against a reporter. “I don’t have a message to the fans,” Trump said.

The fans, no doubt, regard this as the gotcha game of a politically correct press. Even if this is true, an initial reluctance to condemn some of the very worst people in U.S. politics conveys a message. Several years ago, researchers developed an Implicit Association Test — a sort of computerized “blink test” measuring how subjects associate positive and negative words with people of different races. The immediate reaction of a politician to the KKK is a kind of political blink test. The right response is revulsion. And there has generally been a Grand Wizard exception to the prohibition on name-calling.

For a politician on the right, this is an entirely costless Sister Souljah moment. The repeated refusal to seize it conveys an impression of calculation. It indicates a strategy of no enemies to the right.

For some of us, this raises the hardest moral and emotional issue of the current campaign. The Republican nominee came to prominence feeding fears of Mexicans, migrants and Muslims. He refuses to engage in the normal moral and political hygiene of repudiating extremism. I don’t believe that anything close to half of Trump supporters are motivated by racism. But they are willing to tolerate a level of prejudice that should be morally unacceptable in a presidential candidate.

When asked at a House GOP leadership news conference Sept. 13 about former Ku Klux Klan leader David Duke's support for Donald Trump's campaign, vice presidential candidate Mike Pence compared it to Seddique Mateen's attendance at Democrat Hillary Clinton's campaign rally. (Reuters)

Why is this such a problem? Because racial prejudice is not one problem among many in American history. It is the sin that nearly destroyed us. It is a special category of wrong. It is not sufficient to say: I agree with Trump on 90 percent of the issues — on tax reform and energy policy and criminal-justice issues — but dissent on the 10 percent involving systematic religious discrimination, forced expulsion, war crimes, the demonization of refugees and the general dehumanization of the other. These matters are foundational.

History has little sympathy for those who supported Stephen Douglas for his views on tariff policy or internal improvements while playing down his belief that the rights of minorities should be determined by the majority. As Abraham Lincoln saw it, America fought at Gettysburg and Antietam over the most basic questions — how to define the protections and promise of a great republic, as well as the duties we owe to each other as human beings. This remains the central issue of politics — the source of its nobility when it serves human dignity, and a source of dishonor when it reflects baser motives. It is not possible to build the greatness of this nation — this shining example in the conscience of humanity — while forgetting or undermining its deepest ideals.

A refusal to aggressively confront a racially tinged extremism has been taken as a source of validation by white nationalists. They feel emboldened. Duke reports being “overjoyed” that Trump has embraced “most of the issues that I’ve championed for years.” No presidential candidate is responsible for the views of all their supporters. But at least since the 1960s, conservative leaders have felt a responsibility to actively oppose and discredit those elements of the right that identify Americanism with ethnic purity and spin conspiracy theories of Semitic control. Opposing these long-standing tendencies of right-wing nationalism is part of what conservative intellectual and political leadership has meant for decades. The current vacuum of such leadership at the top of the Republican ticket is taken as a cultural signal by both the perpetrators and objects of prejudice.

Or so I would argue. Other Republicans I know and like find my viewpoint morally problematic, because it helps enable the election of Hillary Clinton and the nomination of liberals to the Supreme Court, which would result in irreparable harm to the country. It is a dispute causing a crisis of self-definition among conservatives, straining and rupturing friendships across the movement. That is another legacy of Trump, who will be known for the wounds he leaves behind.

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