Mr. Gonzales's resignation is the latest in a series of high-level departures that has reshaped the end of Mr. Bush's second term. Karl Rove, another of Mr. Bush's close circle of aides from Texas, stepped down two weeks ago.
The official said that the decision was Mr. Gonzales's and that the president accepted it grudgingly. At the same time, the official acknowledged that the turmoil over his tenure as Attorney General had made continuing difficult.
"The unfair treatment that he's been on the receiving end of has been a distraction for the department," the official said.