White House officials were anxious to showcase a step forward in the battle against the coronavirus: an expansion of the use of blood plasma from recovered patients to treat new ones. For nearly two weeks, however, the National Institutes of Health had held up emergency authorization for the treatment, citing lingering concerns over its effectiveness.

So on Wednesday, Aug. 19, Mr. Trump called Dr. Francis S. Collins, the director of the N.I.H., with a blunt message.

“Get it done by Friday,” he demanded…

On the night of the plasma announcement, Dr. Collins was told to show up at the White House, where he was given a coronavirus test and then shunted to the Roosevelt Room as Mr. Trump and others spoke to journalists in the briefing room.

There, Dr. Collins and Dr. Peter Marks, one of the top regulators at the Food and Drug Administration and the person most directly responsible for maintaining the independence and scientific rigor of the vaccine approval process, watched helplessly as the president and other top administration officials oversold plasma’s effectiveness, creating a public relations debacle that reverberated for days.