WASHINGTON — Democratic pressure on Rep. John Conyers, D-Mich., to resign from Congress mounted Tuesday as the number of sexual harassment allegations against him continued to grow and party leaders huddled in conversations about whether he should remain in the House, multiple sources tell NBC News. A report in The Detroit News on Tuesday detailed allegations from a woman who said that the congressman engaged in aggressive sexual behavior toward her while she worked in his congressional office. Those allegations follow similar ones from other women and an admission last week from the congressman that he had reached a settlement with one of them. In an additional sign that Democrats were dropping their support of Conyers, House Minority Leader Nancy Pelosi sent a letter to the House Ethics Committee, which has opened an investigation into the allegations against Conyers, urging it to act "expeditiously" in their investigation. The Congressional Black Caucus, which was co-founded by Conyers, will hold its regularly scheduled meeting Wednesday, but in an unusual move, staff will not be allowed in the room and Conyers was not sent an invitation to attend, one source told NBC News. A photo posted to Twitter appeared to show Conyers boarding a flight Tuesday night from Washington to Detroit. No first-class upgrade for John Conyers tonight on #Delta from #DCA to #DTW. pic.twitter.com/7IQeH7sBAT — Dennis Lennox (@dennislennox) November 29, 2017 Rep. Pramila Jayapal, D-Wash., a member of the Judiciary Committee that Conyers held a ranking position on until he stepped down on Sunday, said Tuesday that Conyers "must resign." "No one ever wants to believe that someone they respect and have regarded as a champion for civil rights issues would abuse their power to harm and harass women," Jayapal said in a statement. "It is not easy for me to reach this conclusion because, as a civil rights activist, I have looked up to Rep. Conyers for decades. I believe these women, I see the pattern and there is only one conclusion — Mr. Conyers must resign.” Jayapal follows Rep. Kathleen Rice, D-N.Y., who called for Conyers' resignation last week. The Congressional Black Caucus chairman,