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House Minority Leader Nancy Pelosi calls for Rep. John Conyers resignation.

Media: Office of Nancy Pelosi

WASHINGTON — Leading Democrats’ support for Rep. John Conyers eroded Thursday, with House Minority Leader Nancy Pelosi calling on the 88-year-old co-founder of the Congressional Black Caucus to resign his seat because of allegations he sexually harassed staffers.

An attorney for Conyers, the longest-serving member of the House, said the Michigan Democrat had no intention of quitting. The congressman was hospitalized in the Detroit area with what a spokesman called stress from a “media assault.”

Pelosi, D-San Francisco, has tried to navigate a treacherous line between loyalty to a veteran Democrat and the powerful Congressional Black Caucus, and support for female accusers coming forward during an explosion of sexual harassment allegations that have toppled major figures in the media and Hollywood and now threaten members of Congress.

After defending him Sunday as an “icon,” even after it was revealed that he had settled a 2015 sexual harassment claim with a former staff member, Pelosi has turned up the pressure on Conyers. He denied guilt in the settlement case, but since then other women have emerged with sexual harassment allegations against him.

On Thursday, Pelosi said Conyers should surrender the House seat he has held since Lyndon Johnson’s presidency.

“Zero tolerance means consequences for everyone,” Pelosi said at a news conference. “No matter how great the legacy, it is no license to harass or discriminate. In fact, it makes it even more disappointing.”

An attorney for Conyers, Arnold Reed, said Pelosi “sure as hell won’t be the one to tell the congressman to leave.” He told the Associated Press that Conyers has “no plans at this juncture to quit” and that the onus was on his accusers to prove their case.

“If there has to be a fight, there will be a fight,” Reed said.

In an interview on the “Today” show Thursday, former Conyers aide Marion Brown said the congressman had propositioned her for sex and “violated my body” during an incident at a Chicago hotel in 2005. She said that when she refused, Conyers asked her to find others who would accommodate him.

Brown said she was the former staffer quoted anonymously in a Nov. 20 Buzzfeed story as saying she was fired in 2014 for refusing Conyers’ advances. She said she had decided to come forward after Conyers denied the allegations publicly, despite the 2015 legal settlement.

“I’m here to say I’m not a liar,” Brown said.

Pelosi had earlier pressured Conyers to give up his post as top Democrat on the House Judiciary Committee, which he said he would do temporarily while the House Ethics Committee investigates the allegations against him. But she had stopped short of calling on him to resign.

The Congressional Black Caucus had resisted calling for Conyers’ resignation. But on Thursday, Rep. James Clyburn of South Carolina, a member of the caucus and the House’s third-ranking Democrat, also called on Conyers to quit.

Clyburn had earlier cautioned against a rush to judgment and suggested that Conyers’ accusers might have “made up” their charges.

Conyers has been in office since 1965 and is one of just seven members of Congress to have served for more than a half century.

The Conyers case is one of several roiling Congress. Sen. Al Franken, D-Minn., has been the subject of several sex harassment allegations, and Texas Republican Rep. Joe Barton said Thursday he would not seek re-election after a nude selfie he had taken was posted to the Internet.

A Bay Area Democratic colleague of Pelosi, Rep. Jackie Speier of Hillsborough, is leading the push to mandate anti-sexual-harassment training for all lawmakers and their staff, which passed Congress on Wednesday, and to overhaul the secretive process by which Congress handles sexual harassment claims.

Another Bay Area Democrat, Rep. Zoe Lofgren of San Jose, is making a bid for Conyers’ job as ranking Democrat on the Judiciary Committee.

Carolyn Lochhead is The San Francisco Chronicle’s Washington correspondent. Email: clochhead@sfchronicle.com Twitter: @carolynlochhead