Van Hollen, 67, posted the announcement on X and discussed it in a television interview. "I am planning to run for the Senate Majority Leader, because this is not about any one individual, but it is about answering the call of the American people," he said. He argued that "the American people called for change" and that Americans "called on us to unrig an economy rigged against working people & fueled by political corruption." In his words: "It's now on us to meet this moment, and to do that we need new leadership."

Schumer, 75, has led the Democratic caucus since 2017. He pointed to the caucus's unity on issues such as cutting costs and ending the war in Iran, and to the party's success in flipping at least eight Senate seats this month. Sen. Kirsten Gillibrand of New York, who chairs the Democratic Senate Campaign Committee, said Schumer "has the support he needs" and that he raised more than half a billion dollars for candidates. Sen. Jacky Rosen and Sen. Sheldon Whitehouse are also in his camp. Sen. Ruben Gallego of Arizona compared the situation to a baseball manager who "takes you to the World Series."

Van Hollen is running as a progressive alternative to the party establishment. He questioned whether the campaign committee "sided with the crypto industry" and AIPAC over progressive candidates. He also faulted Schumer for not using Congress's power of the purse to end the Iran war and for interfering in primary elections. He described the caucus as "in flux."

Counts of who backs whom vary. One tally lists 13 public endorsements for Schumer, among them Gillibrand, Whitehouse and Gallego, and two for Van Hollen: Sen. Bernie Sanders of Vermont, an independent, and Sen.-elect Abdul El-Sayed of Michigan. Van Hollen says more than 10 senators have pledged to support him. Sanders endorsed him quickly and will not back Schumer's bid to remain leader. El-Sayed praised Van Hollen's willingness to "take risks." Sen.-elect Troy Jackson of Maine and Sen. Elissa Slotkin of Michigan have expressed opposition or indifference toward Schumer. Slotkin and Annie Andrews, both newly elected senators, have signaled a desire for generational change without naming a candidate. Seventeen other senators are undecided. Schumer is considered the favorite, and the betting markets Polymarket and Kalshi give him an 83% to 87% chance of winning.

The challenge follows midterm elections in which Democrats won control of both chambers of Congress and gained at least eight Senate seats. Reports credit a backlash against President Donald Trump, and Democrats are poised to win a ninth seat in Alaska, which would give them 56 seats to the Republicans' 44. Other projections put the Democratic total at no fewer than 55, the party's largest midterm Senate gain since 1986.

Schumer is a five-term senator. He was majority leader from 2021 to 2025 and is now minority leader. Van Hollen is a two-term senator who has served since 2017 and is a former House member. He chaired the Democratic campaign operations for both the House and the Senate. He was born in Karachi, Pakistan. During Trump's second term he gained national prominence by opposing the administration's immigration and budget agendas, including cuts affecting NASA, the National Institutes of Health and NOAA. He also traveled about 2,000 miles to El Salvador to meet Kilmar Abrego Garcia, a Maryland resident who was wrongly deported.