House Democrats are investigating an aide’s complaint that newly elected congressman Brian Poindexter made sexually harassing comments toward her during his campaign.

The investigation is being led by an independent firm hired by the Democratic Congressional Campaign Committee (DCCC), the group confirmed in a statement to CNN.

Poindexter defeated Rep. Max Miller, a former Trump adviser whose ex-wife accused him of domestic violence, which he has denied. The unwelcome development comes as Democrats are trying to focus on building out their agenda on the heels of a massive victory in November.

“The DCCC has been made aware of the allegations and takes them seriously,” said Julie Merz, executive director of the campaign group.

In a statement, a spokesperson for Poindexter’s campaign said: “Brian gave what he thought was an innocuous compliment to a volunteer. He heard later that it made her feel uncomfortable and he felt awful.”

The spokesperson added, “When Brian learned about this, we immediately began to work to get to the bottom of it with an outside HR firm. Neither Brian nor the campaign ever wants anyone to feel uncomfortable.”

The Democrats’ campaign arm was alerted about the allegation just before the election by the Blue Dog PAC and the Congressional Progressive Caucus PAC, the groups said in a statement to CNN. Both groups pulled their endorsement of Poindexter until DCCC finishes its investigation.

“The individual requested that we did not disclose any details about this publicly because she did not want her identity becoming public and she wanted an opportunity to determine how she wanted to proceed while protecting herself,” said the statement from both groups. “We respected her desires, and also felt we needed to immediately pull our endorsements pending the investigation being completed. The investigation is ongoing and we await the results.”

Poindexter’s removal from the two group’s endorsement lists came as members were arriving at the Capitol for new member orientation. A source familiar with the matter told CNN that Poindexter was not invited to the new member orientation for the Progressive Caucus.

Cheyenne Hunt, whose group Reckoning Action is providing support to the anonymous woman, told CNN she was contacted by the aide two days before Poindexter flipped Ohio’s 7th District. Hunt described her as a “very low-level staffer” but did not provide additional details in order to protect her anonymity. Hunt declined to discuss the specifics of her allegation.

Lawmakers are in ongoing discussions about how to improve Capitol Hill’s handling of sexual harassment claims, following a spate of complaints about other politicians earlier this year. A group of Democrats are pushing for stricter regulations around conduct as part of a rules package for the full House for next year.

House Minority Leader Hakeem Jeffries has been made aware of the allegation about Poindexter, according to a person familiar with the discussions. His office referred CNN to the campaign arm, pending the ongoing investigation.

Poindexter ran on an economic populist message and played up his background as a union ironworker, but he also leaned into his role as a father. In one early ad, he appeared with his daughters as they ribbed him.

On the campaign trail, Poindexter’s history also became a focal point of Miller’s attacks against him including a 2013 fight with another man at a baseball game, where he was arrested, and a 1998 incident in which he was arrested by police when they suspected he was in possession of crack cocaine.

Poindexter was never charged in either incident and told CNN in an interview in October he never used hard drugs in his life. He also said he is routinely drug tested for his job and has never failed a test.