Yet what once would have caused jaws to drop barely seems to register for long at this point because it is so quickly overshadowed by the next norm-busting statement or action. Five years after he originally kicked off his quest for the presidency, Mr. Trump has said and done so many things once considered out of bounds that his critics no longer even know whether to raise alarms or ignore another palpable bid for attention.

When the president recently promoted a “very impressive” doctor who blames various ailments on demon sperm and says treatments are being developed from alien DNA, it was barely a one-day story. When he endorsed a QAnon adherent running for Congress who warns that the world is controlled by a “global cabal of Satan-worshiping pedophiles,” it did not last that long.

Even on Saturday shortly before midnight, Mr. Trump took no rest from stirring the pot. At 11:09 p.m., just 15 minutes after posting on Twitter a statement mourning the death of his younger brother, he retweeted a message urging the abandonment of cities that he, as president, represents. “Leave Democrat cities,” the message read. “Let them rot.”