“It’s not a coincidence that the same week he did the DACA deal that he just flooded Twitter with a bunch of red meat for the base,” Mr. Conant added. “I think his fundamental problem is he needs to figure out ways to grow his base, and his instinct is instead to double down on what he’s already got. Whenever he tacks to the middle, his numbers tick up. But he just can’t bring himself to move beyond his base.”

That is not how Mr. Trump sees it.

In private, the president and his top aides freely admit that he is engaged in a culture war on behalf of his white, working-class base, a New York billionaire waging war against “politically correct” coastal elites on behalf of his supporters in the South and in the Midwest. He believes the war was foisted upon him by former President Barack Obama and other Democrats — and he is determined to win, current and former aides said.