The first candidate to test the anti-Nancy Pelosi message in 2018 was Rep. Conor Lamb, who narrowly won a March special election in a deeply red Pennsylvania district. Lamb ran on moderate, independent credentials, declaring in a campaign ad that he wouldn’t support Pelosi for speaker.

In the four months since Lamb’s victory, Pelosi has said repeatedly she wants the gavel if Democrats win the House, even as the list of those who say they won’t back her has swelled to more than 40 Democratic candidates of all ideological stripes. Notably, 24 are on the Democratic Congressional Campaign Committee’s Red to Blue list, the districts Democrats hope to flip to take back the majority. Many more are undecided. (Vox is tracking the full list here.)

Behind the scenes in Congress, meanwhile, some Democrats are discussing the details of what a future without Pelosi would look like.

“I think she has much less support than she thinks she does,” said New York Rep. Brian Higgins, a moderate Democrat. “I think that her support is eroding.”

“The conversations are happening,” said another Democratic lawmaker who asked for anonymity to speak candidly. “Change is coming. The leadership team is not going to be the way it looks now.”

It’s not yet clear whether the agitators have the juice (or the votes) to actually unseat Pelosi. The minority leader is confident she’ll prevail.

“Leader Pelosi enjoys the overwhelming support of House Democrats and that will continue into the majority she’s so focused on winning,” said Pelosi spokesperson Drew Hammill in a recent statement to Vox.

But the math is fundamentally daunting. If Democrats win a narrow majority in November, Pelosi will need some newly elected members who ran as Pelosi skeptics to flip-flop, even as resentment of the long-entrenched leadership cadre has grown among established members of the Democratic caucus.

At a moment when the party should be celebrating a victory, unified against President Donald Trump and preparing to roll out their agenda, they’ll instead be fighting among themselves.

The Democratic leadership team is old and well-entrenched

Discontent with Pelosi’s leadership has been growing for years among members who think the party has been stuck in the minority for too long and believe it’s time for someone new at the helm.

“I think there is widespread agreement that we need a rejuvenation of leadership,” Kentucky Rep. John Yarmuth told Vox recently. “How that manifests itself, we’ll see. I think the caucus understands that the party’s changing, the base is changing, and new faces wouldn’t be bad for us.”

But Pelosi’s sway in the caucus can’t be underestimated. She is a master politician who has built alliances with individual factions in her caucus, proving again and again that she can get Democrats to hold the line on tough votes. Even after Democrats were trounced in 2016, Pelosi was able to convince her members to stick together and vote against GOP bills, including last year’s massive tax cuts.

She has also fashioned advancement in the House around her.

“There’s a lot of people in the minority for a long time; anyone who came in after 2010 has never been in the majority,” a Democratic House aide told Vox. “How long are you going to wait to get to be the chairman of a subcommittee?”

The same aide described Pelosi as instrumental in helping loyal House Democrats get their preferred committee assignments.

“She knows what chips she has, and she hands them out accordingly,” the staffer said. “She’s pulling all the strings. If you want to be on a certain committee, that’s her jurisdiction.”

For Democratic members to get prime committee assignments, it takes decades of service in the House, plus a good working relationship with Pelosi. That’s rankled young members, especially those who haven’t known a time when Democrats were in power and could make policy and hand out favors accordingly.

Pelosi also decides who gets to join the ranks of leadership, and hasn’t designated any obvious successor. Her top two lieutenants are Minority Whip Steny Hoyer, 79, and Assistant Democratic Leader Jim Clyburn, 77.

The current makeup of leadership is fairly diverse; Clyburn is African-American, and Rep. Linda Sánchez (D-CA) — the No. 5 Democrat in the House — is the highest-ranking Latina in Congress. But many lawmakers also want diversity of age and ideas in the current caucus reflected in leadership. Reporters have asked Pelosi about these issues many times.

“I am female. I am progressive. What’s your problem?” she shot back at a reporter who recently asked her whether House Democrats should include more politicians who were female, progressive, and younger in leadership.

Former House Democrats who were talked about as being groomed by Pelosi for leadership positions have set their sights elsewhere: Former Maryland Rep. Chris Van Hollen is now a US senator, and rising star Xavier Becerra became California’s attorney general.

Few Democrats — save for Ohio Rep. Tim Ryan — have openly floated their names for the speakership. Ryan, who challenged Pelosi to be House minority leader in 2016, is reportedly considering doing so again.

Pelosi has been dismissive about people who challenge her, recently calling Ryan and Massachusetts Rep. Seth Moulton, another young, vocal anti-Pelosi lawmaker, “inconsequential” to Rolling Stone’s Tim Dickinson in a recent interview.

“She refers to those two as inconsequential?” Higgins said incredulously. “The number of inconsequentials is growing, to the point where all of them are going to be consequential as it relates to who the next leader is going to be. She’s no more powerful than anybody else, but for the power she’s given in the caucus.”

One of Pelosi’s main arguments for remaining at the helm is that she’s best qualified to take on Trump and Republican leadership. Few within the caucus dispute her competency. And as much as Democrats see running against her as a good strategy, she is also doing record-breaking fundraising for the party, hauling in nearly $70 million for Democrats so far this campaign cycle.

A brewing rebellion

Back in March, Rep. Conor Lamb pulled out a win in a conservative Pennsylvania district Democrats didn’t even think they could compete in. While Republicans tried to tie him to Pelosi, Lamb got out in front of their attacks by saying he wouldn’t back her for speaker in a campaign ad.

Lamb’s winning anti-Pelosi playbook is a good strategy — and Democrats know it. It’s clearly popular in purple or red districts they’d like to win. Pelosi understands — and even supports the tactic.

“I think if they had to do that to win the election, I’m all for winning,” she said when asked about Democratic candidates who oppose her at an event in May. “Just win, baby. I think many of them are saying we need ... new leadership. I don’t take offense at that.”

Some Pelosi opponents within the Democratic caucus are observing with a watchful eye as the number of 2018 candidates saying they won’t back Pelosi’s bid for speaker grows to more than 20.

“Those are the ones that are going to give us the majority,” said the unnamed Democratic lawmaker.

Pelosi’s allies say these candidate pledges will be tested during the floor vote for House speaker in November, and they’re confident she can get to the 218 votes she needs to win. They believe these candidates may “fulfill their campaign pledges” by voting against Pelosi in the caucus meeting — which is done by secret ballot. She has won easily in the past, although one-third of the caucus voted against her in 2016 when Tim Ryan challenged her.

“We always assume Pelosi will be challenged,” a senior Democratic aide told Vox. “No one can beat her in the caucus; that is the fundamental problem.”

Pelosi has been in Congress since 1987 and on the Democratic leadership team (starting as House minority whip) since 2002. Elected as the first female House speaker in 2007, she has a reputation both for keeping her caucus in line and for getting major pieces of legislation passed.

“I think Nancy Pelosi is one of the smartest people in Congress,” said Rep. Emanuel Cleaver (D-MO). “I think she’s almost like a shark; I don’t think she sleeps. She is as tough as they come.”

The biggest part of Pelosi’s legacy is inextricably linked with that of former President Barack Obama. Pelosi was a key steward of the Affordable Care Act, helping shepherd the massive health care bill through Congress, and was instrumental in passing the Dodd-Frank regulatory banking bill and fiscal stimulus to help restart the economy following the 2008 financial crisis.

Her track record has certainly won her plenty of allies within her caucus.

“To attack her is to reject so much of the agenda that President Obama passed,” said Rep. Ro Khanna (D-CA), a young progressive Congress member who is one of Pelosi’s staunchest defenders. “She’s a symbol. If you believe in the ACA, if you believe in Dodd-Frank, if you believe in the stimulus bill ... how can you not respect Pelosi’s leadership?”

Pelosi herself has said that she wouldn’t be so focused on running for the speakership post-2018 if she weren’t afraid that the Affordable Care Act would be dismantled, something the Trump administration is very actively trying to do.

“If Hillary had won and the Affordable Care Act was protected — I feel very proprietary about the Affordable Care Act,” Pelosi told Rolling Stone recently. “She’d be a woman in charge, the Affordable Care Act [would be] protected. I could have happily gone home. It’s just a question of, ‘Who can fight this man who’s in the White House? Who really knows the territory?’ None of us is indispensable, but some of us have more experience and confidence in how to get the job done.”

In other words, Pelosi wants to leave on her own terms, when she feels her legacy is secure.

“She wants to choose when she leaves, not be pushed out,” said Thomas Mann, a congressional historian and senior fellow at the Brookings Institution. “And given her success in her job, one can fully understand.”

Who could possibly take the place of Nancy Pelosi?

If you ask Democratic representatives who is on their wish list of new leadership candidates, you frequently get names including Reps. Hakeem Jeffries (NY), Cheri Bustos (IL), Pete Aguilar (CA), David Cicilline (RI), Barbara Lee (CA), Linda Sanchez (CA), and Katherine Clark (MA). Even Cleaver’s name comes up as someone who would be a calm, steady presence to unify the caucus.

Minority Whip Hoyer sees himself as a bridge leader who could get Democrats to 2020 before ushering in a new class of younger House members, but has said he won’t challenge Pelosi outright. Ryan is considering another potential Pelosi challenge, after he took her on in 2016 and lost (peeling off one-third of the caucus in the process).

Though plenty of other names are swirling for leadership positions, there are few other public direct challenges to Pelosi. Lawmakers say they want to elect a diverse group to leadership, when it comes to race, gender, and age. Perhaps most importantly, they want leaders who can offer a new vision and build coalitions within the caucus to stand up to Trump and Republicans.

“When you look at leadership, the top three, you’ve got to look at gravitas,” said Rep. Gerry Connolly (D-VA).

When a challenge to Pelosi is even mentioned, House Democrats refer to it in terms of war.

“People would run if there’s an opening, but I don’t think they’d risk a civil war in the Democratic Party prior to 2020,” Khanna said.

Pelosi’s proponents and even her detractors say Democrats need to stay focused on 2018 before they concern themselves with who will lead them in 2019. But it’s becoming increasingly clear those two things are wrapped up in each other, and there’s a small contingent of lawmakers who say House Democrats need to present new names to challenge Pelosi as part of a larger Democratic change platform.

“There will be an insurgency; I just don’t know who’s leading it. But I assure you, I’m as certain of that as I am that today is Wednesday,” Cleaver told reporters recently.