Sen. Mitt Romney Willard (Mitt) Mitt RomneyGOP set to release controversial Biden report McConnell locks down key GOP votes in Supreme Court fight Will Republicans' rank hypocrisy hinder their rush to replace Ginsburg? MORE (R-Utah) will vote on Friday to allow additional witnesses and documents in President Trump Donald John TrumpBiden leads Trump by 36 points nationally among Latinos: poll Trump dismisses climate change role in fires, says Newsom needs to manage forest better Jimmy Kimmel hits Trump for rallies while hosting Emmy Awards MORE's impeachment trial.

Liz Johnson, a spokesman for Romney, confirmed that the freshman senator will support an initial vote to pave the way for new witnesses and specifically wants to hear from former national security adviser John Bolton John BoltonDiplomacy with China is good for America The Hill's Morning Report - Sponsored by The Air Line Pilots Association - Pence lauds Harris as 'experienced debater'; Trump, Biden diverge over debate prep DOJ launches probe into Bolton book for possible classified information disclosures MORE.

As Romney "has said, he wants to hear from Ambassador Bolton, and he will vote in favor of the motion today to consider witnesses," Johnson tweeted on Friday.

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Romney was widely expected to vote in favor of calling witnesses after emerging as the most vocal GOP senator in favor of hearing new testimony as part of Trump's trial.

He also made the case during a closed-door lunch this week urging his colleagues to back hearing from Bolton after The New York Times reported that he will claim in his forthcoming memoir that President Trump tied Ukraine aid to the country announcing investigations into Democrats.

Romney is the second Republican senator to say they will vote to allow witnesses. Sen. Susan Collins Susan Margaret CollinsMcConnell locks down key GOP votes in Supreme Court fight Most Americans think winner of election should pick next Supreme Court justice: poll Murkowski: Supreme Court nominee should not be taken up before election MORE (R-Maine), a moderate who is up for reelection in November, announced late Thursday night that she will also support the effort.

The rules resolution that passed last week for the trial allows for a vote on whether to request new witnesses or documents.

Democrats will need four Republicans to vote with them to allow witnesses as part of the trial — or three Republicans and Supreme Court Chief Justice John Roberts to step in to break a tie and side with them.

This developing report will be updated.