The Democratic battle for Senate majority leader intensified on Friday as Senator Chris Van Hollen of Maryland put aside his presidential ambitions to push forward in his campaign to challenge Senator Chuck Schumer of New York, the current leader, and lined up supporters.
Appearing at a Democratic event in Denver on the future of the party, Mr. Van Hollen, who announced his challenge on Thursday night, said that he had ruled out a presidential run in 2028 after the sweeping Democratic wins on Nov. 3. Some Democrats had suggested that Mr. Van Hollen was jumping into the majority leader contest to raise his visibility and court progressive voters ahead of 2028, but he said that was not the case.
“I believe that the size and scale of these majorities provides an opportunity for the United States Senate to answer the call of the American people,” Mr. Van Hollen said in disclosing that he was no longer pursuing a White House bid. “I think this is a really important moment for our country, and that we can’t go back to business as usual in the United States Senate.”
He also gained some public backing from senators who will decide the contest, even as he acknowledged he was the “underdog” in the race against Mr. Schumer, who was a key architect and funder of the successful Democratic effort to retake the Senate and has led Democrats there since 2016.
Senator Jeff Merkley, the Oregon Democrat in line to be chairman of the Environment and Public Works Committee, said he was supporting Mr. Van Hollen, posting on social media that he had seen him “rally support for the people against the powerful time and time again.”
Also endorsing Mr. Van Hollen on social media was Peggy Flanagan, the senator-elect from Minnesota, who wrote that Mr. Van Hollen “is the leader and fighter we need to bring about real change.” She was among the newly elected members who had campaigned on calls for a leadership change.
Still, Mr. Van Hollen, who has said he has “more than 10” backers, was believed to be significantly trailing Mr. Schumer in building support for the job. Even before he had an opponent, Mr. Schumer had collected enough commitments from his colleagues to return him for another two-year term as leader, aides said. He remains widely expected to prevail in the secret-ballot election, set for Dec. 1.
With progressive activists and some labor groups stepping up their campaigns on behalf of Mr. Van Hollen, many senators have refrained from making public declarations on what will ultimately be a private vote as a way of staying out of the line of fire.
Funding for the war in Iran is emerging as a central difference in the leadership fight, with Mr. Van Hollen demanding that Democrats withhold support for any money for the military operation even if it means shutting down the government when the current spending authority expires on Dec. 11.
Mr. Schumer has not embraced that tactic. While he has declared that he intends to force an end to the war, he and other leading Democrats have been assessing how to proceed on the funding plan. They have been weighing a temporary extension with some restrictions on the military money until early 2027, when they would hold the majority and likely be able to exert more leverage against the Trump administration.
Despite the unpopularity of the war and the role it played in the Democrats’ election sweep, many Democratic senators are leery of a widespread government shutdown heading into the holidays, fearing it would be difficult to end once it started and would upend their plans for an aggressive start to their new majority in January.
But Mr. Van Hollen said Friday that Democrats needed to be bolder on the war.
“Right now, under our current leadership, we have a situation where they’re not willing to use the most important power we have to end a war, which is to defund it,” Mr. Van Hollen said in Denver.
As they prepared for a takeover, some Democrats also privately raised the idea that the election should be held earlier than Dec. 1, to avoid having the party spend the next few weeks embroiled in a messy internal fight.
In his statement on Thursday endorsing Mr. Schumer, Senator Brian Schatz of Hawaii, who is unopposed in his effort to be elected the No. 2 Democrat in the leadership, said: “We have no time to waste. We must move quickly to vote, unify, and get to work.”
Democrats could vote to move up the election now that the field appears set.
One point that many senators are embracing is a shift in communication strategy that elevates their new members, a significant change in an institution where newcomers are traditionally neither seen nor heard.
“We have enormous energy because of the success of the new members,” said Senator Peter Welch, Democrat of Vermont. “We should put them front and center.”
