“No, I didn’t. I said we’re going to look at it.”

The president has also swung radically in his views of governors and reporters, one day praising them, the next day castigating them. “I really think the media has been very fair,” he said at a briefing last month. By Monday, he no longer thought so. “I wish we had a fair media in this country, and we really don’t,” he said as he denounced one journalist as a “third-rate reporter” and called another one’s question “horrid.”

What remains unclear is whether Mr. Trump does not remember saying things that he later denies saying or is trying to impose his own reality. During a telephone interview last month with Sean Hannity on Fox News, Mr. Trump assailed Gov. Andrew M. Cuomo of New York for saying he needed 30,000 to 40,000 ventilators, suggesting that was exaggerated.

“I have a feeling that a lot of the numbers that are being said in some areas are just bigger than they’re going to be,” the president said. “I don’t believe you need 40,000 or 30,000 ventilators.”

When a reporter at a briefing three days later started a question by noting that “you’ve said repeatedly that you think that some of the equipment that governors are requesting, they don’t actually need,” Mr. Trump cut her off.

“I didn’t say that,” he insisted. “I didn’t say that.”