House Democrats felt the sting Wednesday of the growing progressive, anti-establishment movement that felled one of their rising stars, leaving the future of party leadership up in the air as they head into what could be a big midterm election.

Rep. Joseph Crowley’s defeat, in Tuesday’s New York primary at the hands of a first-time, 28-year-old challenger, left Democrats with no natural heir to the trio of 70-somethings who have led the caucus since early last decade. That the victor, Alexandria ­Ocasio-Cortez, has called for a new generation of leadership at the helm only raised the stakes for the tenure of House Minority Leader Nancy Pelosi.

The California Democrat deflected questions Wednesday about the generational divide that is shaping up ahead of the November elections, as her party has nominated dozens of younger newcomers to politics, energized in reaction to President Trump, who are preaching a new brand of politics.

“Well I’m female, I’m progressive,” Pelosi told reporters at a Wednesday morning news conference, vowing to stay in office. “What’s your problem? Two out of three ain’t bad.”

More than a dozen of these Democratic candidates have joined Ocasio-Cortez in suggesting Pelosi, 78, should move aside for the next generation of leaders.

Rep. Ruben Gallego (Ariz.), a second-term Democrat who opposed Pelosi after the party’s disappointing 2016 elections, said that this crop of candidates would require a leadership team that is “a lot more aggressive and a lot more progressive” to win their support.

“We don’t know if there’s going to be wholesale changes, but whoever the leaders are of this caucus are going to have to be accountable to this new caucus,” Gallego said.

Another renegade, Rep. Seth Moulton (D-Mass.), suggested that there were plenty of smart female leaders who have been stifled by Pelosi’s hold on leadership, as well as the continued service of Reps. Steny H. Hoyer (Md.) and James E. Clyburn (S.C.), the No. 2 and 3 ranking Democrats since the early days of the George W. Bush administration.

“There are extraordinary leaders in our party who never get an opportunity to share their visions,” Moulton said.

However, the Crowley loss produced a countervailing defense from Pelosi’s top lieutenants, who now see a slew of Democratic understudies who have little experience on Capitol Hill. Now, with no experienced people next in line, Pelosi’s and Hoyer’s steady hands are needed more than ever against such a fierce opponent as Trump, her defenders say.

“The fact of the matter is, there’s no one that comes close to what she does, no one. I don’t care what their age is,” said Rep. Anna G. Eshoo (D-Calif.), one of Pelosi’s closest confidantes.

Indeed, the crop of potential leaders is remarkably thin in experience. Any list usually includes Reps. Ben Ray Luján (N.M.), currently chairing the Democratic campaign arm; Cheri Bustos (Ill.), co-chair of the caucus messaging operation; Hakeem Jeffries (N.Y.), co-chair of messaging; Joe Kennedy III (Mass.), political heir to the family dynasty; and Cedric L. Richmond (La.), chair of the Congressional Black Caucus.

Those five have a combined 33 years of service — Pelosi has been in office 31 years — and Luján is the only one to have served in the majority, for all of two years. None has ever chaired a legislative committee, or even been a ranking member, and none has ushered a major piece of legislation into law.

Pelosi’s nearly 16-year tenure atop the caucus has left her deeply unpopular among middle-of-the-road voters, prompting some Democratic candidates to vow to oppose her in the vote for speaker next year if the party won the majority.

That prospect created the chance that Pelosi would not have enough votes from her side of the aisle and would have to abandon her goal of becoming the first person to reclaim the speaker’s gavel, which she lost in 2010, since Sam Rayburn (D-Tex.) in 1955.

But now, in a scenario where younger Democrats demand generational change in leadership, there is no natural successor. “There isn’t anyone that can keep up with her,” Eshoo said of Pelosi.

Crowley, 56, first elected in 1998, the same year as House Speaker Paul D. Ryan (R-Wis.), seemed to have the right mix of experience, fundraising prowess and the appearance of being a relative newcomer compared with Pelosi, Hoyer, 79, and Clyburn, 77. He had long been a champion of a path to citizenship for undocumented immigrants, and he had recently endorsed the most far-reaching health-care proposal, the single-payer legislation advanced by the most liberal contingent of the caucus.

But Ocasio-Cortez ran as an insurgent for change both as a more natural liberal and as a Latina who identified more closely with a district that has grown far more diverse than when Crowley first ran 20 years ago.

“It shows that the country is hungry for a new generation of leadership. It shows that being bold and having a conviction based on politics matters,” said Rep. Ro Khanna (D-Calif.), who two years ago ousted a Democratic incumbent in a primary challenge.

Rep. Barbara Lee (D-Calif.), a leader of the party’s left who narrowly lost the vice chair role in a 2016 race, said Wednesday night that she was beginning to talk to Democrats about seeking Crowley’s job. “The country wants to see Democrats not just unified, but speaking with one voice, on issues like health care, affordable housing, climate change, and debt free college,” she said.

Pelosi’s critics said they believe she can hang on to her position, but it will require her entire leadership team to make a new type of pitch to a much younger caucus.

“The mode of winning in the past was: I have seniority, I have done this and I have raised this type of money, and I think that’s not going to fly with these incoming members of Congress,” Gallego said, suggesting a new focus was afoot. “What are you actually going to do?”