That is why it is not enough for GOP officials to tweet their criticism of Trump. His actions Saturday cannot be erased, even if on Sunday or Monday he buckles to pressure from the public to say more. But there is a way to mitigate the damage he did: a bipartisan congressional resolution that condemns white supremacists and censures the president.

Censure is an old tool in American democracy. It was first directed at Alexander Hamilton when he was in George Washington’s cabinet. Senator Joseph McCarthy was censured; the progressive group MoveOn.org derived its name from arguing against the impeachment of Bill Clinton by calling on Congress to censure him and move on.

Successful censures are sufficiently rare that they carry real political stigma. And a censure on this subject would reassure those who are anxious about the recurrence of the white supremacist cancer that perpetrated decades of domestic terrorism in this country.

Can a step as drastic as censure be justified for an omission in a single statement? It’s an interesting question, but not germane here, for Trump deserves censure on this subject for a long pattern of behavior that I began documenting as early as September 2015.

The article was prompted by this exchange:

Voter: We have a problem in this country. It’s called Muslims. We know our current president is one. Trump: Right. Voter: You know he’s not even an American. Trump: We need this question. This is the first question! Voter: But anyway, we have training camps brewing where they want to kill us. That’s my question, when can we get rid of ’em? Trump: We're going to be looking at a lot of different things. A lot of people are saying that, and you know, a lot of people are saying bad things are happening out there. We’re going to be looking at that and plenty of other things.

That day, Trump chose to exploit rather than to refute paranoid bigotry directed against a minority group when it was voiced right in front of his face with millions watching. And he’d already been exploiting racist Birther delusions for years at that point. By bringing out and tapping into the very worst in others, Trump gained traction.

Ever since, in a world where prosperous countries have descended into ethnic strife in living memory, Trump has maintained a willingness to exploit ethnic tensions for personal gain.

By September 2016, I knew that a Trump win “would make the alt-right more powerful than it has ever been,” as I warned Republicans. Later, when explaining why I would vote for Hillary Clinton, despite being highly averse to her candidacy, I declared:

The most dangerous thing a leader can do in an ethnically diverse country is to stoke ethnic tensions to gain power. One needn’t invoke the Nazis to see that truth. Look to the former Yugoslavia, or Rwanda, Iraq, or Syria. America isn’t on the verge of civil war, but that’s in large part because, while the exploitation of ethnic grievances has always been part of our politics, our leaders have at least held themselves to a certain standard in their public statements. Trump kicked off his campaign by encouraging his followers to think of Mexican migrants as mostly rapists, attacked an American-born judge of Hispanic ancestry, repeatedly savaged Muslims, inspired multiple hate crimes against minorities, used his Twitter platform, with an audience of millions, to retweet and elevate anti-Semites, and inspired more energy and assertiveness from the white supremacist movement than I can ever recall.

After Trump won the presidency, but before he took office, I added, “I fear Trump will continue to stoke ethnic tensions in ways calculated to shore up his support, and that fringe white supremacists and anti-Semites will continue to gain power during his tenure.”

None of this was sorcery. Anyone could’ve seen it coming; and now, alt-right favorites Stephen Bannon, Stephen Miller, and Sebastian Gorka are senior White House advisers. To prevent further damage, Congress should seize the bully pulpit from the White House. With words and silence, Trump has shown his unfitness for it.