Mr. Wheeler provided The Times with a screenshot of the anonymous text he received that included the video, and he said he believed the tipster to be a former Cawthorn campaign aide. Another former aide, Lisa Wiggins, went public in an audio recording released by Mr. Wheeler with her consent, saying, “We all want the ultimate goal of him never serving again.”

Republicans in the state insist that accusations of lawlessness and neglect of his district are more damaging than details of his sex life. Democrats say they are most concerned with Mr. Cawthorn’s support for the protesters who attacked the Capitol on Jan. 6, 2021. A legal effort led by North Carolina Democrats to label him as an “insurrectionist” and constitutionally disqualify him from the ballot failed last month.

But the revelations about his conduct are making a splash. The photos of Mr. Cawthorn in women’s lingerie, first published in Politico, stemmed from a bawdy game aboard a cruise that he took before he was elected to the House, said Melissa Burns, a self-described conservative Republican from Tennessee who witnessed the game, part of an onboard show.

For the finale, the audience was divided into teams, each of which selected a man to dress as a woman, “the sexier ‘she’ is, the more points you get,” Ms. Burns said in an email. Mr. Cawthorn volunteered.

The description is consistent with a description that Mr. Cawthorn provided in a link on Twitter, when he dismissed the photos, saying, “I guess the left thinks goofy vacation photos during a game on a cruise (taken waaay before I ran for Congress) is going to somehow hurt me?”

Ms. Burns also provided a link to a dating app for the cruise from someone identified as “Cawthorn,” using the same photo that was published in Politico, saying, “Im in search of sexy women or couples for some wild sexapades. You wont be disappointed.”

Luke Ball, a spokesman for Mr. Cawthorn, did not deny Ms. Burns’ description of the lingerie game, but he said the dating app was a fake that used the wrong age, wrong hometown and wrong name of the ship.