Another pending investigation appears to focus on how Fox News structured settlements of claims brought by network employees.

Mr. Bharara would presumably be succeeded temporarily by his deputy, Joon H. Kim, a longtime prosecutor and former head of the office’s criminal division.

Also on Friday, the United States attorney for New Jersey, Paul J. Fishman, said in a statement that his resignation had been requested; and in Brooklyn, Robert L. Capers, said he had been “instructed to resign.”

Mr. Bharara had not issued a statement as of Friday evening, when his office was uncertain whether the resignation request applied to him. The announcement that he had been told to resign along with 45 other United States attorneys around the country comes little more than three months after he met with Donald J. Trump, then president-elect, at Trump Tower, and announced afterward that Mr. Trump had asked him to stay on as the United States attorney.

Speaking to reporters after the meeting, Mr. Bharara said that Mr. Trump had asked to see him to discuss “whether or not I’d be prepared to stay on as the United States attorney to do the work as we have done it, independently, without fear or favor for the last seven years.”

“We had a good meeting,” Mr. Bharara said. “I said I would absolutely consider staying on. I agreed to stay on.”

Mr. Bharara also said at the time that he had already spoken with then-Senator Jeff Sessions, the Republican of Alabama who Mr. Trump appointed attorney general. “He also asked that I stay on, and so I expect that I will be continuing,” Mr. Bharara said.