The House on Thursday unanimously passed a resolution calling on special counsel Robert Mueller to release his final report to the public once it's out.

Lawmakers voted 420-0 in favor of the measure from House Judiciary Committee Chairman Jerrold Nadler, D-N.Y. Four Republicans voted "present" on the resolution: Reps. Justin Amash of Michigan, Matt Gaetz of Florida, Thomas Massie of Kentucky, and Paul Gosar of Arizona.

The vote is a clear sign from Congress that members of both parties want to see Mueller's results at the end of what has almost been a two-year investigation. Mueller has been investigating President Trump's alleged collusion with Russia to win the 2016 election.

Democrats and Republicans have been pushing for the release of Mueller's report for different reasons.

[Pressure: House to demand release of Mueller report due to 'overwhelming public interest']

Democrats fear the report may show some wrongdoing by Trump that remains out of the public eye because of the Justice Department's policy of not indicting a sitting president.

"If it basically says, 'Hey, we would have indicted Donald Trump for these offenses but for the fact that there's a policy memo saying we can't,' then I think Congress has to really look at these issues and decide what to do with whatever offenses the Robert Mueller investigation reveals," said Rep. Ted Lieu, D-Calif., this month.

Republicans are out to make sure they understand exactly how Mueller operated in his investigation against Trump.

"Congress and the American people have a right to know how their government conducts business and spends tax dollars," Sen. Chuck Grassley, R-Iowa, said in January. "Special counsel investigations are no different."

The resolution calls on Mueller to release his final report to the public, and also calls on the Justice Department to release it to Congress.

Attorney General William Barr has said only that he would send a summary of Mueller's report to Congress.

[Read more: Trump won't commit to releasing Mueller report to public]