Who Is Ashleigh Merchant, the Lawyer Who Led the Effort to Oust Fani Willis?

Ashleigh Merchant, an Atlanta lawyer representing one of Donald J. Trump’s co-defendants, claimed “vindication” on Friday for her efforts to have Fani T. Willis, the Fulton County district attorney, tossed off the Georgia election interference case.

“The judge clearly agreed with the defense that the actions of Willis are a result of her poor judgment,” Ms. Merchant said in a statement, “and that there is a risk to the future of this case if she doesn’t quickly work to cure her conflict.”

Ms. Merchant was the main force behind the effort to disqualify the district attorney on the grounds that her relationship with Nathan J. Wade, the lawyer she hired to manage the Trump case, constituted a financial conflict of interest.

Though Judge Scott McAfee ruled Friday that Ms. Willis could stay on the case, he sharply criticized her judgment and said Mr. Wade must withdraw, or Ms. Willis must step down. But he also said that the defense lawyers had failed to prove a conflict — and had only demonstrated the appearance of one. Ms. Willis and Mr. Wade have not yet responded to the ruling.

Ms. Merchant, 46, threw the Trump case into turmoil in early January, when she revealed the prosecutors’ relationship in a court filing. That set in motion a series of hearings that turned the table on prosecutors, forcing them to take the stand and endure sharp questioning about their relationship and finances.

A graduate of the University of Florida and its law school, Ms. Merchant, who represents Michael Roman, a former Trump campaign operative charged in the election interference investigation, emerged from the hearings with a national profile, appearing in court as intense and unyielding, with a fast-break style of questioning.

She and her husband, John Merchant, have their own firm, and Ms. Merchant recently became president of the Georgia Association of Criminal Defense Lawyers. She is well connected in local legal circles, and used those connections in seeking to oust Ms. Willis.

Ms. Merchant knew that Mr. Wade and was friends with his former partner and divorce lawyer, Terrence Bradley, whom she called to testify. While Mr. Bradley proved to be an exceedingly reluctant witness, text messages between Ms. Merchant and Mr. Bradley discussing the prosecutors’ romantic relationship were among the most scrutinized evidence in the disqualification effort.

As the hearings unfolded, the prosecution team leveled withering attacks at Ms. Merchant; Ms. Willis, in her testimony, said that “Ms. Merchant’s interests are contrary to democracy.” During one of the hearings, Ms. Merchant told the judge, “They’ve called me everything but a liar today.”