But the latest concerns about Trump are just a crescendo in a long-running drama. Sam Nunberg, a former 2016 Trump-campaign aide, told me that a colleague once approached him and asked if Trump was losing it, saying they had just had the same conversation twice. Nunberg dismissed such concerns, assuring him that it was only because Trump likely wasn’t paying attention the first time.

His speech has changed over time, too. Software programs show that Trump currently speaks at a fourth-to-sixth-grade level. (Politicians are practiced at speaking to wide swaths of Americans, but Obama, for example, according to those speech analyses, spoke at an 11th-grade level in his final news conference as president.) A study last year by two University of Pittsburgh professors examining Trump’s appearances on Fox News found that the quality of his speech was worsening. They studied his comments over a seven-year period ending in 2017—just as his presidency began—and found that he had begun using substantially more “filler words”such as um and uh, though the authors did not conclude that the change signaled cognitive decline.

Even a casual observer can see the disordered and nonlinear thinking behind Trump’s speech. A case in point was Trump’s rally last week in Minneapolis. Within minutes of taking the stage, Trump launched, without explanation, into a dramatic reading of what he imagined was the pillow talk between Peter Strzok and Lisa Page, a pair of former FBI officials who had exchanged text messages critical of the president. He gave no context as to why he was talking about them, leaving it to the audience to fill in the Mall of America–size blanks. Trump never even mentioned that they had worked for the FBI or that Strzok was at one point involved in the Russia investigation—just that they were “lovers” who disliked him. (Still, as theater, it seemed to work. When Trump cooed, “Oh, God. I love you, Lisa!” the audience laughed appreciatively.)

Other people who have worked with Trump in the White House and on the 2016 campaign pushed back on the notion that his mental acuity has eroded over time. “Every president has a super-exaggerated ego and personality in some way,” Tom Bossert, Trump’s former homeland-security adviser and a former official in President George W. Bush’s administration, told me. I asked him if presidents or presidential candidates should be subject to a fitness test measuring whether they’re up to the job. Various psychologists have floated this idea in response to Trump’s behavior. “I’m not sure what the fitness standard would reveal about people who are already wired that way,” Bossert said.

Conventional wisdom in Washington is that impeachment won’t lead to Trump’s removal, but that view rests on Republicans continuing to stay by his side. Even those most loyal to Trump could lose patience if his rash decision making collides with their own interests. Trump’s impulsive decision to pull U.S. troops out of northern Syria last week, setting the stage for Turkey’s attack on America’s Kurdish partners, has already infuriated some of his closest friends in Congress. It was soon after the House, in an overwhelming bipartisan vote, rebuked his Syria gambit on Wednesday that Trump lashed out at Pelosi, prompting her to abruptly walk out of their meeting. (Democrats, of course, are seizing the opportunity. “For those who don’t do politics professionally or even follow it closely: It is getting worse. He is getting worse,” Senator Brian Schatz of Hawaii tweeted last night.)