The more Mr. Trump’s candidacy was said to flatline, the more life I saw in his crowds.

In August 2015, a month after a high-ranking Republican National Committee operative promised me that America would never tolerate a man with no military service disparaging an American military hero, I was standing on a football field in Mobile, Ala., surrounded by 30,000 screaming Trump fans, an unheard-of turnout six months before a primary. Were they mad about the candidates words on Mr. McCain? No. The opposite. “He’s not afraid of anybody,” one woman told me.

Of all the times Donald Trump was done, it is his current status as a supposedly lame duck first-term president that reminds me most of his final months on the trail. Back then, luminaries in his own party were condemning him, calling on him to drop out and researching a late-race change to the top of the ticket.

Much of the country was outraged. The polls were bleak. No politician had ever come back from what Mr. Trump was facing. But then, as now, the view from armchairs in Washington and newsrooms around the country missed something that it was impossible to miss out on the trail. Mr. Trump’s supporters were tired — of Washington, of the media, of waiting. And that fatigue allowed them to overlook a lot. They knew he was flawed but at least, they thought, he was on their side.

On one of Mr. Trump’s primary victory nights, in a ballroom at Mar-a-Lago, surrounded by people in diamonds and silk, I couldn’t help wondering what Mr. Trump’s rally crowds would think of all the money their candidate chose to celebrate with. “Why do people fighting for a raise relate to all of this?” I asked a man in a tuxedo. “Because deep down, they know he’s one of them,” he said.

“Trump sees us,” his supporters would tell me, everywhere we stopped. “You don’t.”

When they couldn’t exactly cheer for him, they found ways to excuse him. Five days after the “Access Hollywood” tape, for example, I asked an older woman in a flowery red dress what she thought of her candidate’s theory of sexual license — as a lone protester was playing the tape on a loop outside a rally venue in Lakeland, Fla.

She smiled. “What person hasn’t said it?” she said.

“I haven’t said it,” I said.

“Well, good for you,” she said.

“You’ve said you’re going to grab women by the … ?” I asked.

“No. Don’t be stupid,” she said, and walked away.