Van Hollen, 67, made the announcement in a statement, saying voters delivered a clear message at the polls.

"It's now on us to meet this moment, and to do that we need new leadership," Van Hollen said. "This is not about any one person — it's about answering the call of the American people. That is why I'm running for Senate Majority Leader."

The challenge comes as progressive activists and a growing number of Democratic lawmakers have called for Schumer, 75, to step aside. Schumer has led Senate Democrats since 2017 but drew sharp criticism from the party's base for what many saw as an insufficiently forceful response to President Trump during a government funding fight in early 2025.

Schumer responded on social media shortly after Van Hollen's announcement, signaling he intends to fight for the job.

"I welcome any discussion about the future of our caucus and the important work ahead," Schumer wrote. "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. I look forward to leading our new Democratic majority and delivering for the American people."

Senate Democrats are set to choose their leader by secret ballot in early December. The winner will preside over a caucus of at least 55 seats, a majority that could grow to 56 depending on the final outcome of the Senate race in Alaska.

Van Hollen, first elected to the Senate in 2016 after more than a decade representing a Maryland suburb of Washington in the House, is among the party's more progressive members. He gained national attention last year for his advocacy on behalf of Kilmar Abrego Garcia, who was wrongfully deported to a prison in El Salvador.

Opposition to Schumer has been building inside the caucus. Earlier this week, Sen. Bernie Sanders, the Vermont independent who caucuses with Democrats, said he would oppose Schumer. Sanders made the announcement alongside Michigan Democrat Elissa Slotkin, who stopped short of explicitly opposing Schumer but told reporters, "I am seeking change."

Several newly elected Democratic senators have also voiced opposition to Schumer's bid, including Minnesota's Peggy Flanagan and Michigan's Abdul El-Sayed.

"I deeply appreciate Senator Schumer," El-Sayed said this week. "But this is about leadership for the American public, and if all we do is kind of go back to what we've been doing in a moment where we've been given a mandate, I worry that we may not earn our mandate."

Other Democrats have publicly backed Schumer, including Arizona's Ruben Gallego, New York's Kirsten Gillibrand and Maryland's Angela Alsobrooks.

The leadership fight will test whether Democrats, fresh off midterm gains, can translate voter energy into a unified agenda — and whether the party's progressive wing can convert its growing influence into control of the Senate floor.