WASHINGTON – Pressure is mounting on the leaders of the Centers for Disease Control and Prevention — from inside and outside the agency — to speak publicly against the White House’s manhandling of CDC research and public health decisions, with career scientists so demoralized they are talking of quitting if President Donald Trump wins re-election.

The situation came to a boiling point last week when William Foege, a giant in public health who led the CDC under Democratic and Republican presidents, called for its current director, Dr. Robert Redfield, to “stand up to a bully” — he meant Trump — even at the risk of being fired.

“Silence becomes complicity,” he said in an interview after a private letter he wrote to Redfield leaked to the news media.

Redfield further infuriated public health experts by issuing a memo, released by the White House, that cleared Vice President Mike Pence to participate in the vice presidential debate Wednesday, even as the White House became a coronavirus hot spot. Nearly a dozen current and former CDC officials — including six who still work there — called the letter highly inappropriate.

And Sen. Patty Murray of Washington, the ranking Democrat on the Senate health committee, said she told Redfield in a private telephone conversation before he testified on Capitol Hill last month that he had to take a stand.

“What I said to him was that my concern was about the agency’s credibility today — and the agency’s credibility that we need as a country in the future,” Murray said in an interview. “This isn’t just about right now. If we lose all the really good scientists there, if people don’t believe the CDC when they put out guidance, what happens in the next flu outbreak? What happens in the next public health crisis?”

No federal health agency has been beaten up quite like the CDC, which is based in Atlanta and prides itself on avoiding Washington partisanship. The Food and Drug Administration did buckle to White House demands to grant emergency approvals for two unproven COVID-19 therapies, but more recently, the FDA withstood enormous pressure — including from Trump — and issued tough new guidelines for emergency approval of a coronavirus vaccine that almost certainly pushes any vaccine release past the election.

The National Institutes of Health has remained above the political fray, and one of its top officials, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, has become a symbol of scientific defiance to Trump. On Friday, Fauci called the White House ceremony announcing Judge Amy Coney Barrett’s nomination to the Supreme Court a “superspreader event.”

But the CDC leadership has proved far more malleable to the president’s will. The White House successfully pressured the agency to revise guidelines on matters like school reopenings, church gatherings and whether cruise ships can sail.

The CDC was forced, over the serious objections of its own scientists, to post coronavirus testing guidelines that suggested asymptomatic people should not be tested. (Redfield later walked that back after the resulting uproar, and it was ultimately reversed.) And the White House thwarted a plan, laid out in a directive drafted last month by Redfield, to require individuals to wear masks on all commercial transportation in the United States.

Supporters of the agency fear the CDC’s reputation will be irrevocably damaged if Redfield does not start more vigorously defending its science.

“What has happened at CDC has been horrifying to see,” said Dr. Mark Rosenberg, who pioneered public health research into gun violence at the CDC but was pushed out after Republicans in Congress effectively cut off funding for his work. “It’s been terribly demoralizing to people who have been working 16- and 17-hour days for weeks or months at a time while taking on COVID-19.”

Redfield declined to comment. Murray said he had given her his assent in their conversation, acknowledging without saying much that he agreed with what she said. A spokesperson for the Department of Health and Human Services, the CDC’s parent agency, said, “The American people are fortunate to have Dr. Redfield leading the CDC.”

The agency’s scientists know that their work will invariably collide with politics; they make decisions and do research on hot-button issues like abortion, teenage pregnancy and gun violence. But they have never seen anything quite like what is happening under Trump.

“We’ve all learned a terrible lesson,” said one CDC official who spoke on the condition of anonymity for fear of being fired. “As much as we want to believe we can operate independently of politics and it’s all about the science, it took just a few months to hobble our ability to steer the course of this pandemic. So we can pretend that the politics don’t matter, but we have been kneecapped.”

Most current and former CDC officials acknowledge that Redfield is in a terrible position, working for a president who has declared all-out war on his agency and who regards its scientists as members of a so-called “deep state” out to get him. Unlike Fauci, he is a political appointee and lacks civil service protections. And unlike the FDA commissioner, he cannot turn to a powerful industry constituency like pharmaceuticals to back him up.

Some say it would be unwise for him to step down, for fear of his successor.

“What happens if 50 of the top scientists at CDC say, ‘We’ve had it, we’re leaving?’ Does that leave the country better off or worse off?” asked Dr. Jeffrey Koplan, who served as the CDC director under Presidents Bill Clinton and George W. Bush and regularly met Redfield for lunch before the pandemic. “I suspect that Dr. Redfield is asking himself the same question.”