Former White House strategist Steve Bannon is expected to testify against longtime Trump associate Roger Stone.

Bannon will appear as a witness for the government during Stone’s trial, a person familiar with the matter told the National Law Journal.

Bannon has not been subpoenaed for his testimony, the person said.

Stone, whose trial begins Nov. 5, is accused of witness tampering, lying to Congress, and obstructing justice. The charges relate to his attempts to reach WikiLeaks during the 2016 presidential campaign.

Bannon and Stone were in contact during the campaign, according to emails obtained by the New York Times, and Stone suggested he had information that WikiLeaks planned to release damaging information on Trump rival Hillary Clinton.

The former White House strategist was fired from his position in 2017 but has recently launched a daily radio show and podcast about the impeachment inquiry that seeks to counter a “well-oiled Democratic media machine.”

Stone has pleaded not guilty.