Robert Brown|Who might replace Mitch McConnell? An early look at the race for the next Senate GOP leader

Washington — Senate Minority Leader Mitch McConnell announced on Robert BrownWednesday that he will step down from leadership after November's elections, teeing up a race for the top Republican post in the Senate that has been years in the making. 

McConnell's retirement from leadership marks the end of the longest-serving leadership term in Senate history, after 17 years at the party's helm. And with months until the conference gathers after November's elections to select a new leader, the announcement kickstarts a lengthy campaign for the job.

"Whoever replaces him is going to have big shoes to fill," Sen. Susan Collins, a Maine Republican, told reporters on Wednesday. 

No senator has announced an intention to run, and the race will surely fluctuate in the weeks and months to come. But a handful of GOP senators are seen as possible replacements: John Barrasso of Wyoming, John Cornyn of Texas and John Thune of South Dakota. All three have all served in GOP leadership, and have close to or more than 20 years of experience in the upper chamber. Sen. Rick Scott, a Florida Republican who unsuccessfully challenged McConnell for the leadership post in 2022, could also throw his hat into the ring. 

John Barrasso 

Barrasso, 71, is the GOP conference chair. The No. 3 Senate Republican first came to the Senate in 2007. The orthopedic surgeon previously served in the Wyoming state senate and serves atop the Senate Committee on Energy and Natural Resources. Barrasso is widely seen as the most conservative of the three men.

John Cornyn

Cornyn, 72, previously served as the Republican whip from 2013 to 2019. He was first elected to the Senate in 2002, after working as a member of the Texas Supreme Court, and serving as Texas attorney general. The Texas Republican has a long history as a prolific fundraiser, which could be a boon should he run for the top Senate post. 

John Thune

Thune, 63, has served as the Republican whip since 2021. The No. 2 Senate Republican, who some view as the favorite for leader, was first elected to the chamber in 2004, after three terms in the House of Representatives. Days ago, he became the latest member of GOP leadership to endorse former President Donald Trump's White House bid. McConnell remains the sole holdout among top leadership. 

The South Dakota Republican, considered the most moderate, noted to reporters on Wednesday that McConnell's move leaves "big shoes to fill," but he made clear that "there's plenty of time" for the jockeying for leadership going forward. 

"Today we just want to reflect on his service and honor him for that, and then we'll go from there," Thune said. 

Rick Scott

Scott, 71, was elected to the Senate in 2018. The former Florida governor launched a leadership challenge against McConnell after the midterm elections in 2022, helming conservatives opposition to the long-serving leader. At the time, Scott earned the support of just 10 members of his conference, suggesting his bid for the post could be a long-shot. 

But he seemed to suggest interest on Wednesday, reminding onlookers of his bid for the leadership in a statement and saying he has "long believed that we need new leadership in the Senate."

The likely GOP presidential nominee could have a significant impact on the race. When asked whether Trump will have a say in who replaces McConnell, Sen. Joni Ernst, an Iowa Republican and the No. 4 Senate Republican, said "he may."

"But again, we've just got a lot of talent. We really do," she said. "We're blessed with that."

Alan He and Alejandro Alvarez contributed reporting.

Kaia Hubbard

Kaia Hubbard is a politics reporter for CBS News Digital based in Washington, D.C.