Ousted FBI Director James Comey will say President Trump pressured him to end an investigation into one of his aides during testimony before a Senate panel probing Russian involvement in the election, according to a report on Wednesday.

Comey, who was fired by Trump on May 9, is working out details of when he would appear before the Senate Intelligence Committee, one of several panels looking into Russia’s interference in the election, along with the FBI and special counsel Robert Mueller, CNN reported, citing a source. His testimony could come as soon as next week.

He has also spoken to Mueller, a former FBI director, about what he will be allowed to reveal during his testimony.

It’s unlikely that Comey will be able to go into detail about the FBI’s ongoing investigation into possible Trump campaign collusion with the Russians, but, the report said, he wants to talk about meetings he had with Trump before being fired.

“The bottom line is he’s going to testify,” the source said. “He’s happy to testify, and he’s happy to cooperate.”

During a White House meeting on Feb. 14, Comey said Trump asked him to shut down a probe into former national security adviser Michael Flynn, whom the president had fired the day before.

“I hope you can let this go,” Trump asked him, according to notes Comey wrote after the meeting that he shared with other FBI officials.

The White House denied Comey’s version of the meeting.

Flynn is under investigation for contacting Russian Ambassador Sergey Kislyak and keeping the White House in the dark about the meetings.