WASHINGTON — Representative John Conyers Jr., the House’s longest-serving lawmaker, does not plan to resign over accusations of sexual harassment despite facing a House Ethics Committee investigation, his lawyer said on Wednesday.

His lawyer, Arnold E. Reed, said in a phone interview that Mr. Conyers, 88, denied any wrongdoing and believed that some people suggesting that he step down, including fellow Democrats, had been scheming for years to push him out as the top Democrat on the House Judiciary Committee.

Asked about the credibility of the accusations of harassment, which have been made by women who were former staff members, Mr. Reed stopped short of calling the women liars.

“You have to ask the women, are they lying or not,” Mr. Reed said. “Mr. Conyers has not engaged in sexual harassment or harassment otherwise with regard to any staffer that he has had.”