The fight over calling additional witnesses at 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 has turned into a struggle for influence between Mitch McConnell Addison (Mitch) Mitchell McConnellOcasio-Cortez to voters: Tell McConnell 'he is playing with fire' with Ginsburg's seat McConnell locks down key GOP votes in Supreme Court fight Video shows NYC subway station renamed after Ruth Bader Ginsburg MORE and 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.

The two Republican leaders — one the Senate majority leader, the other the GOP’s 2012 nominee for president — have two very different agendas.

McConnell has staked his reelection to a seventh term on helping Trump implement his agenda and has made clear that he is closely coordinating trial strategy with the White House.

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Romney doesn't have the immediate pressure of reelection and has told allies that he’s more interested in the role of elder statesman than climbing the Senate’s power ladder.

The Utah Republican made it clear he thought the Senate should 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 and possibly other witnesses in the trial. McConnell is decidedly against hearing from new witnesses.

After a week of tense debate, it appears McConnell, a senator from Kentucky, has emerged as the winner of their battle after convincing a handful of wavering Republicans that voting to subpoena additional witnesses and documents would be a mistake.

Romney has been Trump’s most outspoken Republican critic in the Senate since the retirement of former Sens. Jeff Flake Jeffrey (Jeff) Lane FlakeJeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Republican former Michigan governor says he's voting for Biden Maybe they just don't like cowboys: The president is successful, some just don't like his style MORE (R-Ariz.) and Bob Corker Robert (Bob) Phillips CorkerHas Congress captured Russia policy? Tennessee primary battle turns nasty for Republicans Cheney clashes with Trump MORE (R-Tenn.).

Over the last couple of weeks, he’s sought to influence the course of the trial, just as he’s tried to steer Senate Republicans in other debates, ranging from trade to foreign policy.

“This is not the first time he’s done this, so I think there’s a pattern developing,” said one Republican senator who requested anonymity to discuss internal dynamics.

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“I think he’s talking to persuadables,” the lawmaker said, referring to colleagues who were wavering over how to vote on witnesses.

Many GOP colleagues take Romney’s critiques of Trump with a grain of salt.

“I think most people attribute it to his guttural dislike of the president,” the senator said.

Romney famously delivered a searing speech in March of 2016 warning Republicans not to nominate Trump for the presidency, calling him a “con man,” a “phony” and a “fraud.”

He appeared to have the political momentum Monday morning after The New York Times reported the evening before that Bolton had claimed in an unpublished manuscript that Trump told him he wanted to freeze military aid to Ukraine until officials there announced an investigation into former Vice President Joe Biden Joe BidenBiden leads Trump by 36 points nationally among Latinos: poll GOP set to release controversial Biden report Can Donald Trump maintain new momentum until this November? MORE.

“I think it’s increasingly likely that other Republicans will join those of us who think we should hear from John Bolton,” he said on Monday.

At that moment some reporters were speculating that as many as 54 Republican senators might vote for witnesses. Independent Sen. Angus King Angus KingShakespeare Theatre Company goes virtual for 'Will on the Hill...or Won't They?' On The Trail: How Nancy Pelosi could improbably become president Angus King: Ending election security briefings 'looks like a pre-cover-up' MORE (Maine), who caucuses with Democrats, predicted on Monday that “five or 10” Republicans could vote for witnesses.

Romney had been in talks with a small group of senators, including Sens. 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), Lisa Murkowski Lisa Ann MurkowskiMcConnell 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-Alaska) and Lamar Alexander Andrew (Lamar) Lamar AlexanderMcConnell locks down key GOP votes in Supreme Court fight Alexander backs vote on Trump Supreme Court nominee: What Democrats 'would do if the shoe were on the other foot' Toobin: McConnell engaging in 'greatest act of hypocrisy in American political history' with Ginsburg replacement vote MORE (R-Tenn.), even before the trial started to ensure that McConnell included language in the organizing resolution to guarantee a vote on considering additional witnesses and documents at the end of phase one of the trial.

Senate Republicans say anxiety was running high when they walked into their caucus lunch meeting on Monday, less than 24 hours after the news of Bolton’s manuscript. Romney made a passionate presentation in favor of calling Bolton to testify before the Senate.

But McConnell at the same lunch was able to derail Romney’s momentum by deploying his favorite tactic: invoking Senate process.

McConnell urged his colleagues to hold off on rushing to a decision on whether to call witnesses and wait until the end of the week, after the president’s lawyers had a chance to finish their opening arguments and senators had 16 hours to ask questions of the parties.

McConnell reminded colleagues that they had already voted for an organizing resolution that set up a vote on witnesses and didn’t have to comment on the issue before then.

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“He just reiterated that a couple times as did some other people just to remind us that we have dealt with this and we don’t have to deal with the next step of it until the end of phase one,” Sen. Kevin Cramer Kevin John CramerMomentum growing among Republicans for Supreme Court vote before Election Day On Paycheck Protection Program, streamlined forgiveness is key McConnell shores up GOP support for coronavirus package MORE (R-N.D.) said after the lunch.

The Republican leader put his colleagues almost immediately at ease.

“Clearly we’re in a lot better frame of mind and a lot better shape than we were when we stepped in there,” one GOP senator said of how the collective blood pressure of fellow Republican senators after McConnell was able to blunt Romney’s call for witnesses at the lunch.

Immediately after the meeting, newly appointed Sen. Kelly Loeffler Kelly LoefflerMcConnell locks down key GOP votes in Supreme Court fight Trump supporters chant 'Fill that seat' at North Carolina rally Vulnerable GOP incumbents embrace filling Supreme Court seat this year MORE (R-Ga.), whom McConnell is backing in a Senate primary race against Rep. Doug Collins Douglas (Doug) Allen CollinsVulnerable GOP incumbents embrace filling Supreme Court seat this year Georgia GOP Senate candidates cite abortion in pushing Ginsburg replacement Win by QAnon believer creates new headaches for House GOP MORE (R-Ga.), ripped Romney on Twitter.

“Sadly, my colleague @SenatorRomney wants to appease the left by calling witnesses who will slander the @realDonaldTrump during their 15 minutes of fame. The circus is over. It’s time to move on!” she wrote.

The GOP lawmaker who requested anonymity said Loeffler’s tweet reflected “pent-up frustration” among Senate Republicans.

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Romney on Wednesday downplayed the notion that he’s trying to meld his colleagues’ views on the need for witnesses.

“I have expressed my point of view in the Republican caucus and why I think the way I have, and I’ll let other senators reach their own conclusions,” he said.

He also said that it would be fair for Trump’s lawyers to call their own witnesses if Democrats were able to subpoena Bolton or other witnesses they’re seeking.

Romney deferred to McConnell as the party’s official vote-counter.

A Senate Republican aide familiar with internal discussions said that Romney has merely stated his views publicly in private meetings but is not actively lobbying his colleagues on how to vote.

On Tuesday, the momentum for witnesses among Republicans had slowed, but it was still a hot topic of conversation as they wrestled over the issue at a lunch meeting and then again at a 3 p.m. meeting held in a large room near McConnell’s Capitol office.

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Romney appeared to recognize the momentum among fellow Republicans had shifted against witnesses and did not follow up his forceful call on Monday for Bolton’s testimony with other impassioned arguments at later meetings.

“He said what he had to say and that’s it. He’s been very clear publicly and with his colleagues about his position,” said the Senate aid familiar with internal discussions.

McConnell warned his fellow GOP senators that voting for a motion to consider additional witnesses and subpoenas would give Senate Minority Leader Charles Schumer Chuck SchumerRepublican senator says plans to confirm justice before election 'completely consistent with the precedent' Video of Lindsey Graham arguing against nominating a Supreme Court justice in an election year goes viral Graham signals support for confirming a Supreme Court nominee this year MORE (D-N.Y.) a chance to force votes on multiple subpoenas and could drag out the trial indefinitely.

He warned prolonging the trial would be a painful alternative path to the same result, an acquittal of Trump on the Senate floor.

Sen. Mike Braun Michael BraunPessimism grows as hopes fade for coronavirus deal McConnell shores up GOP support for coronavirus package Patient Protection Pledge offers price transparency MORE (R-Ind.) said McConnell told colleagues at the Tuesday lunch to “look at the big picture in terms of what” voting for witnesses “means” and warned them “whatever we do here sets the stage for what might occur in the future.”

By mid-day Wednesday, Senate Republicans allied with Trump felt the push from fellow Republican senators for additional witnesses and documents had collapsed.

After McConnell and Murkowski, a key swing vote, held a 20- to 30-minute meeting Wednesday morning, the subject of calling additional witnesses didn’t receive any significant discussion at a lunch meeting.

Senators coming out of the meeting, which Murkowski skipped, voiced strong confidence that the question of witnesses had been settled and that McConnell had won.

“For those who agonize over hypothetical situations, let me tell you what the reality is: At this time Democrat Leader Chuck Schumer Chuck SchumerRepublican senator says plans to confirm justice before election 'completely consistent with the precedent' Video of Lindsey Graham arguing against nominating a Supreme Court justice in an election year goes viral Graham signals support for confirming a Supreme Court nominee this year MORE does not have the votes to call any witnesses,” Braun said.

Jordain Carney contributed.