With a second House Democrat calling for his resignation over past allegations of unwanted sexual advances, Rep. John Conyers (D-MI) found himself under pressure Tuesday to step down from his seat in the U.S. House, as a top black lawmaker in Congress said it would be up to the Michigan Democrat to decide his own future.

"Today I met with John and we had a very candid conversation about the seriousness of the allegations against him, which he vehemently denies," said Rep. Cedric Richmond (D-LA), the Chairman of the Congressional Black Caucus.

"Any decision to resign from office before the ethics investigation is complete is John's decision to make," Richmond said in a statement issued late on Tuesday night.

With new press reports about possible sexual misconduct by Conyers involving a former staffer in his office, Richmond told reporters little about the details of the talk, but it was clear that the Black Caucus was trying to urge Conyers to move on.

"I think it is a personal decision," Richmond told reporters, saying he had joined in a "lengthy discussion" with Conyers earlier in the day.

As House members returned to session for the first time since Thanksgiving, Conyers stayed away from the House floor on Tuesday, missing both recorded votes, as other Democrats weighed in on his future - and for some, there was no question about what should happen.

"I have looked up to Rep. Conyers for decades," said Rep. Pramila Jayapal (D-WA), who described herself as someone who had looked up to Conyers "for decades."

"I believe these women, I see the pattern and there is only one conclusion – Mr. Conyers must resign," Jayapal said, becoming the second Democrat in the House to call for his departure.

Earlier on Tuesday, the Detroit News reported allegations from a woman who worked for Conyers from 1997 to 2005; she had discussed the matters with reporters from that newspaper in previous years, but always resisted going on the record, worried that nothing would happen.

"John Conyers is a powerful man in Washington, and nobody wanted to cross him," the story quoted Deanna Maher, explaining why she had not pursued the matter further.

And in the halls of Congress, there were rumblings of even more stories being heard by other black Democrats.

A photograph posted on social media Tuesday evening seemed to show Conyers on a Delta flight going back to his home of Detroit.

Meanwhile, House Democratic Leader Nancy Pelosi sent a letter to the House Ethics Committee asking for swift reviews of any allegations of sexual misconduct leveled against Conyers.

"We are at a watershed moment for our country in the fight against sexual harassment and discrimination," Pelosi wrote, as she urged the panel to ask for extra resources if needed.

"The Committee on Ethics has a great responsibility to proceed expeditiously as well as fairly into any investigation of credible harassment and discrimination allegations," Pelosi added.

Conyers is recognized as the Dean of the House, the currently longest serving House member, first elected in 1964.

Rep. Don Young (R-AK), elected in 1973, is next in seniority.

On Sunday, Pelosi referred to Conyers as an "icon," but has quickly moved to put pressure on him over these allegations of unwanted advances, touching, and possible sexual harassment.