“I deny these allegations, many of which were raised by documents reportedly paid for by a partisan alt-right blogger,” Mr. Conyers said in a statement on Sunday. “I very much look forward to vindicating myself and my family before the House Committee on Ethics.”

Mr. Conyers said that he would “like very much to remain as ranking member,” but had “come to believe that my presence as ranking member on the committee would not serve these efforts while the Ethics Committee investigation is pending.”

His lawyer, Arnold E. Reed, said in a phone interview on Sunday that Mr. Conyers had taken several days to decide to step aside from his committee post because he did not want to make an “off the cuff” move. Mr. Conyers spoke with several family members and deliberated during the Thanksgiving holiday before determining that the allegations had become too much of a distraction, the lawyer said.

“He wanted time to think about this and reach a conclusion that he was comfortable with. And it was the right thing to do in his mind,” Mr. Reed said. “He is maintaining that he did not do anything wrong. He is maintaining his innocence. This is a temporary stepping aside his position as ranking member so this can be a completely transparent and unfettered investigation.”

On Wednesday, Mr. Reed had said in an interview that Mr. Conyers believed that some of those suggesting that he step down, including fellow Democrats, had been scheming for years to push him out of his Judiciary post.

A senior House Democratic aide said the decision had come after days of effort by Ms. Pelosi, who was working with Mr. Conyers to find a way for him to step aside gracefully. Ms. Pelosi hinted at as much on “Meet the Press,” where she said, before Mr. Conyers’s announcement, that she expected him to “do the right thing.”

The interview showed the delicate position that Ms. Pelosi is in. She declined to say that Mr. Conyers should step down, calling him an “icon in our country” who had done “a great deal to protect women.” Ms. Pelosi later came under some criticism on social media for those remarks.