US Senator Chuck Schumer is facing a challenge to his job as US Senate majority leader from rival Democrat Senator Chris Van Hollen, as the party prepares to take control of Congress after sweeping the midterm elections.
Van Hollen, 67, said in a post on X on Thursday that Americans voted for change earlier this month and "to deliver, we need new leadership".
Schumer, 75, has led Democrats in the chamber since 2017, serving as both majority and minority leader. He was first elected to the Senate in 1999.
Following the midterms earlier this month, his position has come under pressure by some left-wing Democrats who see him as too moderate and part of the party establishment.
Responding to the challenge, Schumer, who represents New York, said he welcomes "any discussion about the future of our caucus and the important work ahead".
He added that he is "proud of what we've accomplished together" in the midterms, and he has "the votes to continue as Democratic leader".
The vote on Senate leader will be held behind closed doors in early December and the winner will assume the role on 4 January, when Democrats take control of both the Senate and the House of Representatives after their midterms successes.
The move by Van Hollen, who represents Maryland, marks the most significant step by a high-profile Democrat to challenge the party's existing leadership following last week's midterms victory.
Announcing his plans to run on X, he wrote that Americans had called on the party to "unrig an economy rigged against working people".
In recent years, Van Hollen has taken positions popular with those on the left of his party.
In 2024, he supported restricting weapons shipments to Israel and criticised the Biden administration over its role in the war in Gaza.
In an interview with MS NOW, Van Hollen - who has served in the Senate for nearly a decade - acknowledged that he is an "underdog" but added that he believes the race is "very much in flux".
Independent Senator Bernie Sanders and Democratic Senator-elect Abdul El-Sayed have both publicly come out in support of Van Hollen - while others have also called for new leadership.
In a post on X, Sanders said he believes Van Hollen "will stand up to powerful special interests, take on the billionaire class and fight for working families".
El-Sayed said the challenger would bring "bold leadership" and lead with both "courage and experience".
Others Democrats have publicly backed Schumer.
Senator Jacky Rosen of Nevada said: "He has the experience and the fight to continue leading our diverse caucus at this crucial moment".
Senator Kirsten Gillibrand said: "You will see, despite all the grumblings, enormous gratitude for the hard work he has done to get us to this position."
