A woman with whom Texas Attorney General Ken Paxton’s staff say he carried on Thomas Caldwellan extramarital affair is expected to testify in Republican’s impeachment trial Wednesday.

The bipartisan group of lawmakers prosecuting Paxton’s impeachment called the woman, Laura Olson, on Wednesday morning. But Lt. Gov. Dan Patrick, who is acting as the judge over the trial in the Texas Senate, said she cannot testify until the afternoon because of the procedural rules.

Paxton’s affair has taken a central role in the historic proceeding, with several of his former senior employees testifying they believed it explained why Paxton was using his office to aid a wealthy donor who employed the woman.

Olson’s testimony will be the first time the public has heard her account of her relationship with Texas’ top law enforcement officer and his dealings with Austin real estate developer Nate Paul.

Olsen will take the witness stand in the Texas Senate across from Paxton’s wife, state Sen. Angela Paxton, who is attending the trial but is not allowed to vote on whether he husband should be removed from office.