More than 2,000 former US Department of Justice (DOJ) employees signed a letter on Sunday calling for US Attorney General William Barr’s resignation, condemning President Donald Trump and Barr’s interference in the sentencing of Trump associate Roger Stone.

The letter cites the DOJ Manual, which calls on officials to “be impartial and insulated from political influence,” in its prosecutorial powers in particular. It commends the four prosecutors’ work on Stone’s sentencing memo. The four resigned last week following the dispute with Barr over these recommendations.

“Governments that use the enormous power of law enforcement to punish their enemies and reward their allies are not constitutional republics; they are autocracies,” the letter states. Signatories include former US Attorneys, Office of Legal Policy Counsel, Special Counsel, US Marshals and others.

Barr said in an ABC interview on Thursday he would not be “bullied or influenced by anybody,” including the president, stating that Trump’s tweets make it difficult to do his job. “I cannot do my job here at the department with a constant background commentary that undercuts me,” he said.

Stone was found guilty in November of lying to the House Intelligence Committee, witness tampering and concealing evidence from investigators.

Judge Amy Berman Jackson is scheduled to sentence Roger Stone on February 20 in the US District Court for the District of Columbia.