I was late for breakfast with Colorado’s governor, John Hickenlooper. We were in Manhattan, on the same September day that President Trump gave a speech at the United Nations, the one where the delegates laughed out loud at him. By the time I reached Madison Avenue, I found the street entirely blocked off by police barriers.

“How do I get from here to there?” I asked a cop. I thought it was a reasonable question.

“You don’t,” he replied, summing up the Trump era in a single phrase.

So I stood there, along with a score of other New Yorkers, waiting for Mr. Trump to pass. At last his motorcade appeared, and as it did, people on both sides of the street spontaneously raised their arms and flipped our chief executive the bird.

As the barricades fell and I rushed to meet Mr. Hickenlooper, I wondered if the governor — on the cusp of a possible run for president — could also inspire such passions.