Sen. Al Franken was a prominent critic of the Trump administration and was sometimes mentioned as a potential Democratic presidential candidate. (Eric Thayer/Bloomberg News)

Sen. Al Franken, who until two weeks ago was one of the Democratic Party’s brightest stars, is now fighting for political survival amid mounting allegations that he committed sexual abuse and a solidifying resolve within his party to take a hard line on any such transgressions.

The senator from Minnesota’s problems were compounded Thursday on two fronts: A fifth accuser, this one an Army veteran, stepped forward with an account similar to three others who have claimed they were groped while posing for pictures with the former “Saturday Night Live” star. Meanwhile, a move by top Democrats to force out another lawmaker showed a growing eagerness to immunize the party on an issue that is turning into a social movement.

In the House, Minority Leader Nancy Pelosi (D-Calif.) and her three deputies called on Rep. John Conyers Jr. (D-Mich.), the longest-serving member of Congress, to resign in the face of accusations that he mistreated female aides for more than two decades. “Zero tolerance means consequences for everyone,” Pelosi said.

Although Pelosi did not mention Franken, her comment had immediate repercussions on the other side of the Capitol, where the comedian-turned-senator has become one of his party’s sharpest and most effective combatants against the Trump administration. His name has frequently been mentioned as a possible 2020 presidential contender.

“In light of Pelosi demanding that Conyers step down, I don’t know how Franken can survive it,” said Jim Manley, who was a longtime top aide to former Senate Majority Leader Harry M. Reid, a Nevada Democrat.

None of his fellow Senate Democrats has yet called for Franken to resign; the party line has been that he should be dealt with by the Ethics Committee.

But more and more Democrats outside the Senate are saying that it has become untenable for Franken to remain in office, despite the fact that his alleged offenses are arguably of a lesser degree than those of the other cases that have dominated the news. Conyers, for example, has been accused of demanding sexual favors of female aides.

In the House on Thursday, two more Democrats — caucus chairman Joseph Crowley (N.Y.) and Tim Ryan (D-Ohio) — called on both Franken and Conyers to leave Congress. Earlier in the week, Rep. Kathleen Rice (D-N.Y.) said both men should resign.

Privately, many other Democrats are coming to the same conclusion about Franken, said political strategist Lis Smith. “I haven’t talked to a Democrat behind the scenes who thinks this guy should stay,” Smith said.

Franken indicated Thursday that he plans to stay put. “I know I’ve got a lot of work to do to regain people’s trust,” he said in a statement provided to The Washington Post. “But I remain committed to continuing to work as hard as I can for my constituents.”

Democrats do not want to be seen as having a double standard on the issue of sexual abuse, party strategists said.

They frequently bring up the fact that President Trump sits in the Oval Office after boasting of crude acts on a now-famous “Access Hollywood” video, and despite the fact that more than a dozen women have come forward saying he actually behaved that way with them.

Sexual abuse has also become a central question in a Dec. 12 special Senate election in Alabama. Democrats have a chance of winning a seat in that deeply conservative state, thanks largely to the fact that the GOP nominee, former Alabama chief justice Roy Moore, has been accused of making sexual advances to teenage girls when he was in his 30s.

But there are signs that the allegations against Franken may be weighing down efforts by Democrats to gain momentum by using the issue.

Some recent polls show Moore may be recovering, and Trump aides privately credit that in part to accusations against Frank and media figures drawing attention away from the embattled GOP candidate, according to two people familiar with White House thinking.

Concerns about Franken appear to be growing among Democratic donors. Guy Cecil, chairman of Priorities USA, among the largest and most active Democratic super PACs, tweeted Thursday: “This is not complicated. Conyers should resign. Franken should resign. Moore should drop out or be defeated. Hypocrisy on the other side doesn’t justify hypocrisy on our side. Period.”

Racial questions also weigh as Congress considers how to deal with two of its members. Conyers is African American; Franken is white.

“There are, to my count, five of these allegations against Al Franken. There are four, three or four, against the congressman,” Conyers’s attorney, Arnold Reed, said, in a Detroit news conference where he rejected Pelosi’s call for his client to resign. “At the end of the day, I would suspect that Nancy Pelosi is going to have to explain, what is the dis­cern­ible difference between Al Franken and John Conyers?”

Franken’s defenders note that there are additional differences between his situation and those of other men who have been accused of sexual abuse.

The initial complaint against him came on Nov. 16 when Los Angeles radio news anchor Leeann Tweeden said he forcibly kissed her while rehearsing a skit for an overseas USO show in 2006, two years before he was elected to the Senate. She also produced a photo that appeared to show Franken poised to grab her breasts as she slept aboard a military aircraft, as if playing a prank.

Franken apologized, although he said his recollection of the kissing incident differed from Tweeden’s.

The episode gave Trump an opening. “The Al Frankenstien picture is really bad, speaks a thousand words,” Trump tweeted. “Where do his hands go in pictures 2, 3, 4, 5 & 6 while she sleeps?”

Subsequently, four other women came forward claiming Franken had groped them — the most recent being former military police officer Stephanie Kemplin, who said she was traumatized when she posed for a picture with Franken during a USO tour in Kuwait in December 2003.

“When he put his arm around me, he groped my right breast,” Kemplin told CNN. “He kept his hand all the way over on my breast. I’ve never had a man put their arm around me and then cup my breast.”

Franken, who issued yet another apology, has expressed a willingness to submit his fate to the Ethics Committee. On Thursday, the panel confirmed that it has opened a “preliminary inquiry” into the matter.

The process could take weeks or even months to come to a resolution.

In the meantime, Franken’s strategy has been to attempt to carry on as usual. He has given interviews to Minnesota news outlets and held his regular weekly breakfast with constituents visiting from his home state. He issued a Thanksgiving Day apology in which he said, “I feel terribly that I’ve made some women feel badly and for that I am so sorry, and I want to make sure that never happens again.”

Franken has also attended committee hearings and regular meetings with Senate colleagues.

On Thursday, Franken stepped out of the lunch in the Capitol’s Lyndon B. Johnson Room and went into a hallway behind the Senate chamber to take a phone call.

While seated in the hallway, he took greetings from Senate Minority Leader Charles E. Schumer (D-N.Y.), one of his closest friends in the Senate and a fellow Brooklyn native. As Schumer headed into the lunch, he ignored a question about whether he stands by Franken.

Sen. Richard J. Blumenthal (D-Conn.), who serves alongside Franken on the Judiciary Committee, where Franken has won plaudits from fellow Democrats for his aggressive questioning of Attorney General Jeff Sessions, said that Franken “could continue to be a strong voice for reason and sanity.” But, Blumenthal added, “in no way does his continuing robust involvement in the committee detract from the need to hold him accountable.”

The list of powerful men who have been felled by allegations of sexual assault and harassment grows on a near-daily basis, with NBC “Today” show host Matt Lauer and humorist Garrison Keillor joining their ranks this week.

Keillor, the folksy radio personality known best as the former impresario of the “Prairie Home Companion” series, was fired by Minnesota Public Radio for “inappropriate behavior.” A day earlier, he had come to his fellow Minnesotan’s defense in a Washington Post op-ed headlined: “Al Franken should resign? That’s absurd.”

Josh Dawsey contributed to this report.