(CNN)Once a fixture at the administration's coronavirus briefings, Dr. Deborah Birx has confided to aides and friends that she has become so unhappy with what she sees as her diminished role as coordinator of the White House coronavirus task force that she is not certain how much longer she can serve in her position, sources familiar with her thinking tell CNN.

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Birx has told people around her that she is "distressed" with the direction of the task force, describing the situation inside the nation's response to the coronavirus as nightmarish.

According to people familiar with her thinking, Birx views Dr. Scott Atlas, a recent addition to the task force, as an unhealthy influence on President Donald Trump's thinking when it comes to the virus.

"The President has found somebody who matches what he wants to believe," a source close to Birx said of her view of Atlas's relationship with Trump. "There is no doubt that she feels that her role has been diminished."

Birx believes Atlas is feeding the President misleading information about the efficacy of face masks for controlling the spread of the virus, the source said. Trump, whose rallies draw crowds of supporters who refuse to wear masks, has repeatedly mocked Democratic rival Joe Biden for using them. Read more at CNN