The House Judiciary Committee heard testimony Wednesday from a federal prosecutor and another witness who have accused Attorney General William P. Barr and his top deputies of acting “based on political considerations” and a desire to appease President Trump.

Aaron Zelinsky, an assistant U.S. attorney in Maryland formerly detailed to the Russia investigation by special prosecutor Robert S. Mueller III, told the panel that prosecutors involved in the criminal trial of Trump’s friend Roger Stone experienced “heavy pressure from the highest levels of the Department of Justice” to give Stone “a break” by requesting a lighter sentence.

Zelinsky was joined by John Elias, an official in the Justice Department’s antitrust division, who said Barr ordered staff to investigate marijuana company mergers simply because of his “personal dislike” of the nature of their underlying business.

Also appearing before the panel were former U.S. attorney general Michael B. Mukasey and former deputy attorney general Donald Ayer, who has publicly called on Barr to step down.

In his testimony, Ayer said Barr “poses the greatest threat in my lifetime to our rule of law,” while Mukasey dismissed allegations that the Justice Department has become politicized under Barr.

Meanwhile, Barr has accepted an invitation from the panel’s chairman, Rep. Jerrold Nadler (D-N.Y.), to appear for a “general oversight hearing” on July 28, Barr’s spokeswoman, Kerri Kupec, said in a tweet Wednesday. According to a Judiciary Committee spokesman, the Justice Department contacted the panel on Tuesday regarding a date for Barr’s testimony to avoid a subpoena for the attorney general.