Senate Republicans are poised to make a historic decision on Wednesday when they'll gather behind closed doors to select their new party leader -- and President-elect Donald Trump's influence in undeniable as he insists that whoever be selected support his ability to install recess appointments to his Cabinet.

With Trump's victory and Senate Republican's majority secured, the lead up to the race has intensified the jockeying between the three major contenders for the position: Sen. John Thune, Sen. John Cornyn and Sen. Rick Scott.

The leadership election, slated to occur just one day after the Senate returns from its monthlong election recess, will see Senate Republicans selecting their first new leader since 2007, when current Republican Leader Mitch McConnell first won the job. McConnell is the longest-serving party leader in United States history, but announced earlier this year he'd be stepping aside after the election.

Thune, a South Dakota Republican who currently serves as the No. 2 Republican, is somewhat of a front-runner in the race. He has served as the party whip for the last six years and in that time has notched a number of policy wins for the party, and has been working behind closed doors to whip support for the role for months. Thune said he keeps in regular contact with Trump and his team, but the two have at times had an icy relationship.

Running against Thune is Cornyn, a Texas Republican and another established GOP leader who served as the party's whip for the six years prior to Thune before being term-limited out of the role. Though Cornyn has a slightly more conservative track record than Thune, he also faced ire from Trump for his support of the bipartisan gun safety bill that passed in the wake of the shooting in Uvalde, Texas.

Also vying for the role is Sen. Rick Scott, a Florida Republican who just won reelection. Scott has attempted to brand himself as the most Trump-aligned of the contenders, but is less popular among some of his Senate colleagues after a stint atop the Senate GOP's campaign arm in 2022 led to a less-than-successful night for Senate Republicans.

Trump won't get a vote in this secret-ballot race, but his influence over it is palpable.

Many Republicans see Trump's comfortable victory in Tuesday's elections coupled with Senate Republicans' new majority as a sweeping mandate to implement Trump's policies, and as such, potential party leaders seem to be cozying up to Trump ahead of the vote.

Trump has not yet endorsed a specific candidate for the race, and it's unclear whether he ultimately will. Instead, Trump has attempted to exert influence over the race by arguing that whoever is slated to fill the role supports a modification to what has become the Senate's normal operating procedure to allow him to temporarily install appointments to federal vacancies without Senate approval during the Senate recesses.

"Any Republican Senator seeking the coveted LEADERSHIP position in the United States Senate must agree to Recess Appointments (in the Senate!), without which we will not be able to get people confirmed in a timely manner. Sometimes the votes can take two years, or more. This is what they did four years ago, and we cannot let it happen again. We need positions filled IMMEDIATELY!" Trump wrote on his social media platform on Sunday.

Recess appointments are permitted by the constitution, and allow presidents to fill federal vacancies during Senate recesses. Though once a regular occurrence, the Senate has operated in such a way as to block all recess appointments since former President Barack Obama's first term. Allowing recess appointments for Trump's second term could allow controversial nominees who may otherwise fail to get the support they need from the GOP-controlled Senate to serve for nearly two years without Senate approval.

None of the top contenders have ruled out supporting the use of these recess appointments, and their responses to Trump's post show how far each is willing to go to show that they're on Trump's side.

Though Thune said in an interview on Thursday that his "preference" would be for Trump to stay out of the Senate leadership race, he issued a statement Sunday night following Trump's post affirming his commitment to installing Trump's Cabinet, and not ruling out the appointments Trump is seeking.

"One thing is clear: We must act quickly and decisively to get the president's cabinet and other nominees in place as soon as possible to start delivering on the mandate we've been sent to execute, and all options are on the table to make that happen, including recess appointments," Thune said in a statement. "We cannot let Chuck Schumer and Senate Democrats block the will of the American people."

Cornyn meanwhile discussed the use of recess appointments with Trump prior to his post, per a source familiar. In a post on X Sunday afternoon, Cornyn affirmed his support, noting that if he is elected leader, he will keep the Senate in session continuously until nominees are confirmed.

"It is unacceptable for Senate Ds to blockade President @realDonaldTrump's cabinet appointments. If they do, we will stay in session, including weekends, until they relent. Additionally, the Constitution expressly confers the power on the President to make recess appointments," Cornyn wrote.

Almost immediately after Trump posted on Sunday, Scott posted on X that he was in lockstep with Trump on this policy.

"100% agree. I will do whatever it takes to get your nominations through as quickly as possible," Scott wrote, reposting Trump's post.

A small handful of senators have come out publicly to endorse their chosen candidate.

Scott, for his part, has picked up endorsements from some of Trump's most out-and-proud supporters in the Senate as well as a number of Trump-aligned outside voices, including Robert F. Kennedy and Elon Musk.

But this critical race has a very small constituency: only Republican senators serving in the incoming Senate get a vote. ABC News has not yet reported a projection in the Pennsylvania Senate race, but that means only about 52 people will get to cast ballots.

Senators are also shielded behind closed doors and by secret ballot in this race. In order to win the election, a candidate must amass a simple majority of the vote. If all candidates fail to get a simple majority, the lowest vote earner is eliminated from the process, and senators vote again.

Because of the secret nature of the vote, it's unclear how much of an influence any outside factor, including Trump, will ultimately wield.

Newly elected incoming senators including Bernie Moreno of Ohio, West Virginia Gov. Jim Justice, Reps. Jim Banks of Indiana and John Curtis of Utah and Tim Sheehy of Montana will all be in attendance to cast votes.

Sen. JD Vance, who is now the vice president-elect, is also eligible to cast a vote in the election if he so chooses, but his team has not yet said whether he ultimately will attend Wednesday's vote.

In addition to the closely-watched race for party leader, a number of other positions will also be selected during Wednesday's vote. Sen. John Barrasso, a Wyoming Republican, is running unopposed to becoming the No. 2 Senate Republican. Sen. Joni Ernst, an Iowa Republican, and Sen. Tom Cotton, the Republican from Arkansas, are in a race to become the conference chair. Additional down-ballot races will also be voted on Wednesday.