More than 1,100 former Justice Department officials have called for the resignation of Attorney General William Barr in an open letter published Sunday.

It comes after Justice Department leadership said it would lower the amount of prison time it would seek for Trump ally Roger Stone, reversing the initial sentencing recommendation brought by DOJ prosecutors. This prompted the four DOJ lawyers who prosecuted Stone to quit the case.

The open letter, signed by former DOJ employees who served under Democratic and Republican presidencies, accuses Barr of “doing the President’s personal bidding” and calls for his resignation.

“It is unheard of for the Department’s top leaders to overrule line prosecutors, who are following established policies, in order to give preferential treatment to a close associate of the President, as Attorney General Barr did in the Stone case,” the letter states. “Those actions, and the damage they have done to the Department of Justice’s reputation for integrity and the rule of law, require Mr. Barr to resign.”

It also notes, “because we have little expectation (that Barr will resign), it falls to the Department’s career officials to take appropriate action to uphold their oaths of office and defend nonpartisan, apolitical justice.”

The letter points to the Department of Justice’s rules for its lawyers, noting that the Department’s legal decisions “must be impartial and insulated from political influence.”

“And yet, President Trump and Attorney General Barr have openly and repeatedly flouted this fundamental principle,” the letter states.

The four DOJ lawyers who resigned from the case had recommended an original sentence of up to nine years for Stone. President Donald Trump tweeted that the recommendation was “horrible and very unfair” and, within hours, DOJ leadership intervened and instead recommended three to four years. Trump had congratulated Barr for “taking charge” of the Stone case, raising questions and criticism about the attorney general’s independence from the President.

Justice Department spokeswoman Kerri Kupec told the Daily Beast on Tuesday that the decision to override the sentencing recommendations was made Monday night, before Trump’s tweet.

Barr previously told ABC News on Thursday that he will not “be bullied or influenced by anybody” and that the President’s tweets “make it impossible for me to do my job.”

“I’m going to do what I think is right,” Barr said. “I cannot do my job here at the department with a constant background commentary that undercuts me.”

The Justice Department did not immediately respond to a request to comment from TIME.

The letter commends the four prosecutors who withdrew from the Stone case. “We call on every DOJ employee to follow their heroic example,” it states, advising staff to report any future abuses to the Inspector General, the Office of Professional Responsibility and Congress.

The list of former DOJ officials who signed off on the letter is being maintained and updated by nonprofit Protect Democracy.

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Write to Sanya Mansoor at sanya.mansoor@time.com.