The leadership election is set for Dec. 1 behind closed doors, and Schumer, who has led Senate Democrats since 2017, has locked in support from a growing list of colleagues. Van Hollen, a senior member of the Appropriations Committee, announced his bid Friday, saying Democrats need a choice.

“It’s important to give Senate Democrats a choice,” Van Hollen said at a press conference in Denver. “That’s what we just gave voters — all over the country — a choice. They chose change, and I think that the Democratic caucus needs to be open to new ideas, a different way of governing and a different way of conducting and approaching politics.”

Van Hollen also told reporters he will not run for president in 2028, reversing earlier signals that he was “kicking the tires” on a potential bid.

Schumer responded shortly after Van Hollen’s announcement, writing that he welcomes discussion about the caucus’s future but already has the votes to continue as leader. “I’m proud of what we’ve accomplished together — 55 seats and counting is an amazing result – and I have the votes to continue serving as Democratic Leader,” Schumer said. “I look forward to leading our new Democratic majority and delivering for the American people.”

Van Hollen has picked up backing from some newly elected senators. Michigan Sen.-elect Abdul El-Sayed told the Michigan Advance he planned to support Van Hollen, saying, “I was the first to be calling on him as the next leader, so I would love to see him run, and I’d love to see him as our next leader.” Minnesota Sen.-elect Peggy Flanagan posted her support on social media, writing that Van Hollen “is the leader and fighter we need to bring about real change, so no American is left behind.”

“Minnesotans are demanding change,” she wrote. “Democrats need to deliver. That starts with new voices in our leadership.”

Michigan Sen. Elissa Slotkin and Vermont independent Sen. Bernie Sanders, who caucuses with Democrats, both indicated earlier this week they were open to voting for a challenger. Sanders said he would not vote for Schumer, while Slotkin said she would only support a candidate with a clear plan for governing in the majority.

“I think whoever wants to run this caucus should come forward with a plan on how they’re going to govern differently, what they’re going to do in the first 100 days to put money in people’s pockets and then in particular how they’re going to communicate differently,” Slotkin said, adding she did not intend to challenge Schumer herself.

Maine Sen.-elect Troy Jackson told reporters on Nov. 6 that he would not support Schumer, according to WGME. “I’ve already said, I told Senator Schumer I’m going to support somebody else, so that’s no different now,” Jackson said.

But Schumer’s allies quickly rallied behind him. Hawaii Sen. Brian Schatz, who is likely to become whip next year, said voters “sent a clear message: they want us to lower costs, end a needless war, and fight corruption.”

“Our caucus has the right to have a conversation about the path ahead, but we have no time to waste. We must move quickly to vote, unify, and get to work. I endorse Senator Schumer for leader and will be voting for him in the caucus election,” Schatz said.

Maine independent Sen. Angus King, who caucuses with Democrats, praised Schumer as “one of the principal architects of the most successful election in modern history” and asked, “Why would you fire the manager when you just won the World Series?”

Wisconsin Sen. Tammy Baldwin echoed the baseball metaphor: “The Brewers just had a record season, and next year is not the time to change our management. The same is true in the Senate. Under Leader Schumer, Democrats won at least 55 seats. He earned his position as Majority Leader next Congress, and together we’ll deliver for Wisconsin families.”

Arizona Sen. Mark Kelly said Schumer “worked really hard to get this majority.” Nevada Sens. Jacky Rosen and Catherine Cortez Masto both endorsed Schumer on social media Thursday night. Rosen wrote that Schumer “did the work to deliver what will soon be a 56-seat Senate majority against all odds,” while Cortez Masto said he “was instrumental in Democrats flipping 8 – soon to be 9 – Senate seats and securing a historic majority.”

Rhode Island Sen. Jack Reed initially said he would “wait to see what develops” but then confirmed he planned to support Schumer. Virginia Sen. Tim Kaine declined to share his vote, saying, “All the discussions about caucus leadership I’m having with my colleagues. I’m not trying to give messages through the press.”

The leadership fight comes as Democrats prepare to take the majority next Congress after a stronger-than-expected midterm showing. Van Hollen argues the party must embrace change, while Schumer and his supporters say continuity and experience are assets as Democrats prepare to govern.

The closed-door caucus vote is scheduled for Dec. 1.