Old allies and public health experts have expressed disgust at her accommodations to Mr. Trump and, more so, at the performance of the federal response she is supposed to be leading against the most devastating public health crisis in a century. Ms. Pelosi said she had lost confidence in Dr. Birx, while Mr. Trump called her “pathetic” after she suggested the obvious: The coronavirus is in a “new phase” and is spreading rampantly.

“Her credibility, particularly in the H.I.V.-AIDS community, has taken an enormous hit in the last five months,” said Mitchell Warren, the executive director of AVAC, a global advocacy group fighting to end H.I.V./AIDS, who has worked closely with Dr. Birx. “She is absolutely data driven, so it is incredibly disappointing to see her coordinating a national response which has not at all been best in class, but has been a disaster on many levels.”…

But some say Dr. Birx is at least partly responsible for mismanaging the government’s response. A report issued by the State Department’s inspector general in February relayed criticism of her AIDS program leadership team, which was called “dictatorial” and “autocratic.” She has been critical of the Centers for Disease Control and Prevention, and some public health experts view her as partly responsible for sidelining the agency.

Some also fault her for offering unduly rosy assessments of the pandemic — both in public and in private. In April, she told officials in the White House Situation Room that the United States was in good shape.