In the past, the $100,000 check from Mr. Trump has been made out to the Small Business Administration initiative to help veteran entrepreneurs, to the Office of the Surgeon General to fight the opioid epidemic, and to the National Institute on Alcohol Abuse and Alcoholism, among other places.

But on Friday, Kayleigh McEnany, the White House press secretary, did not just reveal that the president was sending his salary to the Department of Health and Human Services to help “support the efforts being undertaken to confront, contain and combat the coronavirus.”

She also displayed the president’s private bank account and routing numbers.

The $100,000 check she held up like a prop appeared to be a real check from Capital One, complete with the relevant details. An administration official said mock checks were never used in the briefing.