Yes, Mr. Trump’s policy positions were poorly defined, but these days, most candidates’ positions are. And yes, he had little support from the Republican Party leadership. But many of us thought even this might be a positive if it forced him to focus on “making deals” rather than on Washington’s usual ideological posturing. He was never going to fulfill all of his over-the-top promises, but we believed that his administration might achieve some meaningful successes.

In my writing, I tried to steer this administration in the right direction. During the presidential primaries, the blog I helped organize, called the Journal of American Greatness, was one of the leading voices supporting certain themes of Trump’s campaign. (Michael Anton, now a National Security Council adviser, was our most prolific writer.) Then, after the election, I founded a quarterly journal, American Affairs, largely to question elements of what is often called the neoliberal policy consensus — totally open borders for capital and labor; transferring power from national governments to transnational technocracies; unfettered markets; and democracy promotion as the sole premise of foreign policy. In other words, the disappointing legacy we inherited from the Bushes and the Clintons that helped pave the way to Mr. Trump’s election.

In this role, as one of the few people in the media who has been somewhat sympathetic to Mr. Trump, I am often asked to comment on his surprise victory, or more recently on his statements, policies and the gusher of news pouring out of this White House. For months, despite increasing chaos and incoherence, I have given Mr. Trump the benefit of the doubt: “No, I don’t really think he is a racist,” I have told skeptical audiences. “Yes, he says some stupid things, but none of it really matters; he’s not really that incompetent.” Or: “They’ve made some mistakes, but it’s still early.”

It’s no longer early. Not only has the president failed to make the course corrections necessary to save his administration, but his increasingly appalling conduct will continue to repel anyone who might once have been inclined to work with him.

From the very start of his run, one of the most serious charges against Mr. Trump was that he panders to racists. Many of his supporters, myself included, managed to convince ourselves that his more outrageous comments — such as the Judge Gonzalo Curiel controversy or his initial hesitance to disavow David Duke’s endorsement — were merely Bidenesque gaffes committed during the heat of a campaign.

It is now clear that we were deluding ourselves. Either Mr. Trump is genuinely sympathetic to the David Duke types, or he is so obtuse as to be utterly incapable of learning from his worst mistakes. Either way, he continues to prove his harshest critics right.

Mr. Trump once boasted that he could shoot someone in the street and not lose voters. Well, someone was just killed in the street by a white supremacist in Charlottesville. His refusal this weekend to specifically and immediately denounce the groups responsible for this intolerable violence was both morally disgusting and monumentally stupid. In this, Mr. Trump failed perhaps the easiest imaginable test of presidential leadership. Rather than advance a vision of national unity that he claims to represent, his indefensible equivocation can only inflame the most vicious forces of division within our country.