“For Donald Trump to stand on the stage with Hillary Clinton, side by side, in the same frame, both with the same kind of podium, equal time and the moderator treating each with equal respect — that has a normalizing effect,” said Dan Senor, who was also an adviser to Romney’s 2012 campaign and was primarily responsible for helping to prepare Romney’s running mate, Paul Ryan, for his one debate against Joe Biden. Senor wasn’t speaking as a cheerleader for Trump. In fact he has come out publicly against Trump’s bid.

There are nonetheless perils aplenty for Trump on Monday night. While he would be best served by a somber shade — perhaps for his tresses as well as his temper — his most fervent fans prefer a sassy one. Is there a color that bridges the difference and does it all?

He has never debated someone one-on-one. His primary debates were crowded affairs, with anywhere from four to 11 candidates onstage. He didn’t have to fill all that much time or speak with all that much specificity. In only three of those debates did he talk for more than 20 minutes. In only one of those three did he talk for more than 30. Even so he circled back repeatedly to his polls, to the wall, to making America great again, to winning so much that we’ll tire of winning.

On Monday night, if he and Clinton get relatively equal time, he might have to talk for some 45 minutes, and he hasn’t shown the depth of knowledge to do that without sounding like a broken record. “I think it’s going to be hard for him to physically, emotionally, intellectually and analytically hold it together for that amount of time,” Senor said.

And it’s improbable that the moderator, Lester Holt, will be as gentle as Matt Lauer was during that much-derided forum a few weeks ago. Since then there has been a marked change in the way that both TV interviewers and writers have treated Trump. It was particularly noticeable after Trump’s ludicrous claim that Clinton had started the birther movement.

“He’s got to deal with the recent willingness of broadcast journalists to press him when he’s lying,” said Bob Kerrey, the former governor and senator from Nebraska. “The ice has begun to break around him.” Kerrey singled out a recent appearance by Trump on Fox News, where even Bill O’Reilly was somewhat combative with him, trying to pin him down on his call for profiling in the fight against terrorism.