Just days after returning from Kenosha, Wis., where he staunchly backed law enforcement and did not mention the name of Jacob Blake, the Black man shot seven times in the back by the police, Mr. Trump issued an order on Friday to purge the federal government of racial sensitivity training that his White House called “divisive, anti-American propaganda.”

The president then spent much of the weekend tweeting about his action, presenting himself as a warrior against identity politics. “This is a sickness that cannot be allowed to continue,” he wrote of such programs. “Please report any sightings so we can quickly extinguish!” He reposted a tweet from a conservative outlet hailing his order: “Sorry liberals! How to be Anti-White 101 is permanently cancelled!”

Not in generations has a sitting president so overtly declared himself the candidate of white America. While Mr. Trump’s campaign sought to temper the culture war messaging at the Republican National Convention last month by showcasing Black and Hispanic supporters who denied that he is a racist, the president himself has increasingly made appeals to the grievances of white supporters a centerpiece of his campaign to win a second term.