The US House of Representatives is expected to pass a bill on Tuesday that will force the release of investigative files related to the late pedophile Jeffrey Epstein, after Donald Trump and his Republican allies backed down from their opposition amid a scandal that has dogged the president since his return to the White House.

Though Trump has for months dismissed the uproar over the government’s handling of the Epstein case as a “Democrat hoax”, he signaled his support for the House bill over the weekend, and said he would sign the measure if it reaches his desk. On Tuesday morning, the Republican speaker, Mike Johnson, said he would vote for it, making it nearly certain it will be passed when the chamber votes on the bill in the afternoon.

“I’m going to vote to move this forward,” Johnson told reporters. “I think it could be close to a unanimous vote.”

However, the legislation’s fate remains unclear in the Senate, where the Republican majority leader, John Thune, has not said if he will put it up for a vote. Even as he announced his support, Johnson criticized the measure for not doing enough to protect victims of Epstein, a financier who died in 2019 by what investigators determined was suicide while he was awaiting trial on sex-trafficking charges.

“Everybody here, all the Republicans, want to go on record to show we’re for maximum transparency, but they also want to note that we’re demanding that this stuff get corrected before it is ever moves through the process and is complete,” Johnson said.

Any changes to the bill made by the Senate would require it to be approved again by the House, probably delaying its enactment.

The Epstein case returned dramatically to the public eye in July, when the justice department released a memo saying it had nothing further to disclose about the investigation. That flew in the face of statements made by Trump and his top officials that indicated they would release more information about Epstein’s offenses and ties to global elites once they took office.

Shortly after, four dissident Republicans in the House and all Democrats banded together to force a vote on a bill to release the investigative files, over Johnson’s objections.

The leaders of that effort cheered the imminent vote, with the Democratic congressman Ro Khanna calling Tuesday “the first day of real reckoning for the Epstein class”.

“Because survivors spoke up, because of their courage, the truth is finally going to come out, and when it comes out, this country is really going to have a moral reckoning. How did we allow this to happen?” Khanna said at a press conference, adding that the case was “one of the most horrific and disgusting corruption scandals in our country’s history.”

Trump’s friendship with Epstein has had staying power in American politics as the late disgraced financier had links to many other rich and powerful figures in the US and overseas. The president’s dramatic shift came after it became increasingly apparent that the bill would pass the GOP-controlled House, most likely with significant support from Republican lawmakers. Trump in recent days changed his approach from outright opposition to declarations of indifference.

“I DON’T CARE!” the president wrote in a social media post on Sunday. “All I do care about is that Republicans get BACK ON POINT.”

Speaking in the Oval Office on Monday, Trump said he did not want the Epstein scandal to “deflect” from the White House’s successes, and claimed it was a “hoax” and “a Democrat problem”.

“We’ll give them everything,” he told reporters. “Let the Senate look at it, let anybody look at it, but don’t talk about it too much, because honestly, I don’t want to take it away from us.”

Thomas Massie, an iconoclastic Republican congressman who frequently defies Trump and joined with Khanna to pursue the files’ release, noted the president’s reversal on the Epstein issue.

“We fought the president, the attorney general, the FBI director, the speaker of the House and the vice-president to get this win,” he said. “But they’re on our side today, though, so let’s give them some credit as well.”

In July, Khanna and Massie turned to a procedural tactic known as a discharge petition to circumvent House leadership and compel a vote on their bill, the Epstein Files Transparency Act, if a majority of the 435-member House signs on.

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Johnson went to extraordinary lengths to avoid a vote on the the measure, which splintered his conference. Democrats accused the speaker of delaying the swearing-in of the Arizona Democrat Adelita Grijalva to prevent her from becoming the decisive 218th signatory. She signed her name to the petition moments after officially taking office last week.

Thune’s office declined to comment on what the senator planned to do about the bill. The Democratic Senate minority leader, Chuck Schumer, announced that as soon as the bill passes the House, he will move to immediately debate and vote on it in the upper chamber.

“Republicans have spent months trying to protect Donald Trump and hide what’s in the files. Americans are tired of waiting and are demanding to see the truth. If Leader Thune tries to bury the bill, I’ll stop him,” Schumer said in a statement.

As president, Trump has the authority to order the justice department to release the documents in its possession, as he has previously done with the government records related to the assassinations of Martin Luther King Jr and John F Kennedy.

Emails released last week by a House committee that has opened a separate inquiry into the scandal showed Epstein believed Trump “knew about the girls”, though it was not clear what that phrase meant. The White House said the released emails contained no proof of wrongdoing by Trump.

Last week, the president instructed the justice department to investigate prominent Democrats’ ties to Epstein. The US attorney general, Pam Bondi, who earlier this year said a review of the files revealed no further investigative leads, replied to Trump that she would get on it right away and has appointed a prosecutor to lead the effort.

The Epstein scandal is a core issue for a swathe of Trump’s rightwing base, some of whom believe in conspiracy theories that surround Epstein and his coterie of powerful friends and associates. Unlike many other issues, the Epstein files have prompted rebellions from Trump’s supporters in politics and the media, who have called on the president to follow through on his campaign promise to release them.

Meanwhile, several Epstein survivors have ramped up pressure on Congress and Trump to advance the measure.

“It’s time that we put the political agendas and party affiliations to the side. This is a human issue. This is about children,” survivor Haley Robson said at the press conference. “There is no place in society for exploitation, sexual crimes or exploitation of women.”

She then addressed her comments to Trump, saying: “While I do understand that your position has changed on the Epstein files, and I’m grateful that you have pledged to sign this bill, I can’t help to be skeptical of what the agenda is.”

On Monday night, activists projected an image of Trump and Epstein on to the justice department building, accompanied by the message: “Release the files now.”