WASHINGTON (Reuters) - The U.S. House of Representatives overwhelmingly approved a non-binding resolution on Thursday calling for Special Counsel Robert Mueller’s upcoming report on his probe into Russia’s role in the 2016 election to be released to Congress and the public.

FILE PHOTO: Special Counsel Robert Mueller (R) departs after briefing members of the U.S. Senate on his investigation into potential collusion between Russia and the Trump campaign on Capitol Hill in Washington, U.S., June 21, 2017. REUTERS/Joshua Roberts/File Photo

The 420-0 House vote, with four conservative Republican lawmakers voting “present,” gave Democrats who control the chamber a political victory and put pressure on Attorney General William Barr to make the report public after Mueller submits it to him. But the resolution does not force Barr to do so.

The measure faces an uncertain future in the Republican-led Senate. A bid by the Senate’s top Democrat, Chuck Schumer, to have the resolution approved by voice vote after the House’s action was thwarted by Republican Senator Lindsey Graham.

Mueller has been investigating since May 2017 whether Trump’s campaign conspired with Moscow and whether the president has unlawfully tried to obstruct the probe. Trump has denied collusion and obstruction. Russia has denied election interference. Mueller has not indicated when he will complete the report, though an announcement on Thursday about the coming departure of a senior prosecutor on his team stoked speculation that it could be soon.

Justice Department regulations governing special counsels give Barr latitude in deciding how much of the report to make public. The rules require him to notify the top Democrats and Republicans on the House and Senate judiciary committees after Mueller completes his probe. They do not require release of the report but also do not prevent Barr from giving the entire document to Congress.

The resolution, introduced last week by the heads of six House oversight committees that are investigating Trump, calls on Barr to make public everything in the Mueller report that is not expressly prohibited by law and to provide the entire document to Congress.

The vote put the vast majority of House Republicans on record as supporting broad disclosure of the report on an investigation that Trump has called a “witch hunt” led by “thugs.”

Four members of the conservative House Freedom Caucus, a group strongly allied with Trump, voted “present.” The four were Representatives Justin Amash, Matt Gaetz, Thomas Massie and Paul Gosar. Seven lawmakers - four Democrats and three Republicans - did not vote.

‘FULL TRANSPARENCY’

Representative Jerry Nadler, chairman of the House Judiciary Committee and author of the resolution, said on the House floor: “It is important that Congress stand up for the principle of full transparency at a time when the president has publicly attacked the Russia investigation more than 1,100 times and counting.”

The House panel’s top Republican, Representative Doug Collins, backed the resolution but described it as a restatement of the regulations that give Barr the option of releasing the full report.

“During his confirmation, Attorney General Barr said he wants to be transparent with Congress and the public, consistent with the rules and the law. We have no reason to think Attorney General Barr would back away from those statements,” Collins said.

Barr, a Trump nominee who took over the Justice Department last month, replaced Jeff Sessions, who the president ousted in November after long complaining that the former senator had recused himself in 2017 from overseeing the Russia probe.

As Schumer tried to get the Mueller resolution approved by voice vote, the senator said on the Senate floor: “The American people have an undeniable right to see the results of that investigation.”

Graham, a Trump ally, blocked the action unless Democrats backed a move they oppose: the appointment of a special counsel to investigate Democratic former President Barack Obama’s administration’s handling of an investigation into Hillary Clinton’s use of a private email server as secretary of state and FBI surveillance of a Trump campaign official.

Some Democrats have voiced concern that Barr could withhold evidence of possible misconduct by Trump, under Justice Department policies that oppose bringing criminal charges against a sitting president and discourage releasing explanations when a person has not been charged with a crime.

House Democrats already have vowed to subpoena the report and go to court if necessary to win its full release.

The Mueller investigation so far has resulted in criminal charges against 34 individuals and three companies, seven guilty pleas and one conviction following a jury trial.