Pelosi and Schumer, who in the past voted for the walls they now denounce, deny they support open borders, but their refusal to support barriers is nearly the same thing. With the border nearly 2,000 miles long, barriers are essential at many points.

Trump can say all this day after day in city after city, and it might change nothing. So be it. He still has, as he said again Saturday, the avenue of declaring an emergency and using other funds.

He also could work with private groups trying to raise money through contributions. Kris Kobach, the former Kansas secretary of state, is advising one group, “We Build the Wall,’’ and he told The New York Times the president gave the project his blessing.

No one can know what, if anything, will gain Trump a second term. But sometimes the key to winning is behaving as if there is something worse than losing. In Trump’s case, that would be giving up on securing the border and failing to put America first.