Donald Trump has done great damage to more than his presidency. With his remarks about the tragedy in Charlottesville, Trump dramatically increased the nourishment and encouragement he has been feeding the racist right.

Activists respond to signals, and racist right leaders saw Donald Trump, standing in front of the gilded elevators in Trump Tower. frantically waving them on.

In his misplaced and myopic commitment to a dishonest and evenhanded assessment of blame, Trump affirmed the white nationalist protests of those who support him, and warned their opponents that more were coming. It’s every bit as awful as you imagine, and maybe a little bit worse.

Whether or not the president realized what he was doing, his audience certainly understood; racist leaders got the message.

Klansman David Duke, whom Trump condemns every few years under duress, tweeted his gratitude:  “Thank you President Trump for your honesty & courage to tell the truth about #Charlottesville & condemn the leftist terrorists in BLM/Antifa.”

Richard Spencer, the white supremacist “identitarian,” didn’t even wait for the meltdown press conference, explaining that Trump’s earlier condemnation of the violence wasn’t to be taken seriously. “Only a dumb person,” he said, “would take those lines seriously,” identifying Trump as the “first true authentic nationalist in my lifetime” to be president.

Although a far larger number of Americans, including Trump’s putative allies in the Republican Party, were appalled by Trump’s response, social movements don’t need majorities to mobilize, nor to make a difference.

Seeing an ally in the Oval Office, especially one beleaguered by mainstream politicians, fuels the difficult work of building a movement. Trump’s encouragement makes it easier to go to a meeting after work, stay later and talk to another potential convert, to find the temerity to go out in public and face people protesting against you. And if the counterprotesters outnumber you, it’s even easier to find justification for carrying arms.

Violence and confrontation brings attention to the white nationalist movement and, like their president, its activists welcome any attention. The president of the United States has accepted them, and effectively endorsed at least part of their cause in defending the Confederate monuments. In the face of policy defeats (the monuments are coming down), Trump’s support is feeding a new “Lost Cause” story.

Trump has expanded the space and attention available for white nationalist advocates, and you can expect them to try to fill it. They will be met by larger crowds of anti-racist activists and, at least sometimes, a smaller would-be vanguard of antifa activists ready to fight. Every confrontation will feed the beast.

Eager street fighters ready for violent confrontation with each other won’t make the police work easier. Indeed, first hand reports from Charlottesville credit antifa fighters with protecting non-violent activists–and even saving lives. They stepped in when police were not around. Depending upon committed amateurs to keep the peace is hardly a recipe for peace and civility. It’s particularly awful that sets of young men with very different political commitments are prepared to see themselves as the good guy with a gun–or shield or stick.

What’s even worse, whenever and however the Trump presidency ends, those who see him as their champion will view his failed presidency as yet another indictment of the degradation of the political mainstream, all the more reason to take to the streets–carrying Confederate and Nazi paraphernalia, brandishing whatever weapons they’re allowed to show.

Imagine what the president of the United States could do to counter this growing danger, then look at your Twitter feed tomorrow morning. I fear you won’t feel better.