A growing number of Democratic senators support reforming the party’s superdelegate system — a move that would dilute their own power in the presidential nominating process but satisfy Bernie Sanders and his millions of supporters as Democrats move to unify for the general election.

Politico interviewed nearly 20 of Sanders’ colleagues over the past week and found a surprisingly strong appetite for change, including among influential members of the party establishment such as Sen. Tim Kaine (D-Va.), a top prospect for vice president. More than half the senators surveyed support at least lowering the number of superdelegates, and all but two said the party should take up the matter at next month’s convention in Philadelphia, despite the potential for a high-profile intraparty feud at a critical moment in the campaign.

The findings point to growing momentum among Democrats for changing a system that’s been criticized for giving party bigwigs undue sway over the nominee at the expense of the grass roots. But powerful Democratic Party constituencies, including the Congressional Black Caucus, are firmly opposed. And lawmakers who are open to reform disagree over how far-reaching it should be.

“It’s not useful to anyone to be in a position where you could potentially overturn the will of the electorate. I mean nobody likes this, and it undermines public confidence,” said Sen. Brian Schatz of Hawaii, who has spoken privately to a dozen other Democratic senators about the matter. His support for scrapping superdelegates isn’t shared by a majority of the Senate Democratic Caucus, but it could be a starting point for negotiations.

Some senators declined to comment, not wanting to alienate activists or party bosses. And a significant number of Democrats said they’re fine with however it plays out but just want to put the drama over nominating rules to rest.

“I want Bernie in the fold, I want him enthusiastic,” said Sen. Sherrod Brown of Ohio, another potential VP choice. “I’m fine with whatever they negotiate, I just don’t care about superdelegates. I don’t care about the whole thing.”

The 714 superdelegates — members of Congress, governors, state party chairs and other Democratic elites — are meant to give battle-hardened Democrats a steadying hand on the selection process, as a bulwark against a candidate who might rouse the grass roots and romp to the nomination but end up being a poor general election standard-bearer.

But Sanders and his supporters argue the system gives too much power to party elites and could lead to a scenario in which members of Congress defy the will of voters. At points during the campaign, Sanders argued that Hillary Clinton might not have been able to win without superdelegates, though ultimately they were not the difference-maker.

Even Donald Trump has knocked the Democrats’ rules as undemocratic.

The sustained push by Sanders supporters, combined with Clinton’s interest in winning over his backers, is likely to push the issue onto the agenda in Philadelphia.

“It’s something we should debate,” said Sen. Tom Carper of Delaware. “There’s probably a middle ground somewhere between get rid of every single superdelegate and maintaining the status quo.”

The conflict over party rules started brewing many months before any primary or caucus votes were cast. A number of Democrats in Congress who serve as superdelegates lined up behind Clinton, giving her a significant delegate lead even before the Iowa caucuses. After the New Hampshire primary, the inherent conflict was evident: Sanders crushed Clinton in the Granite State, but the state’s Democratic senator, Jeanne Shaheen, had already endorsed Clinton.

That rankled many in the party, particularly liberals.

“I’d like to see the Democratic Party be as democratic as possible,” said Sen. Tammy Baldwin of Wisconsin.

Her view is shared by Sen. Elizabeth Warren (D-Mass.) and a clutch of other liberal lawmakers. But they have powerful opposition.

The Congressional Black Caucus and Sen. Chuck Schumer of New York, the future Democratic leader, oppose tinkering with the system. CBC Chairman G.K. Butterfield of North Carolina said he was “outraged” to even hear about it, arguing that “eliminating superdelegates would be discriminatory and prevent African-American officeholders from participating in the convention.”

“I’m fine with the superdelegates,” Schumer said in an interview. “Caucuses harness the energy of individual people, they’re legitimate. Superdelegates harness those who worked in the party a long time. I’m for having a nice mixture.”

Given the resistance of Schumer and other longtime senators like Bill Nelson of Florida, proponents of eliminating the superdelegate system altogether may just be making an initial bid ahead of the talks in Philadelphia. Several supporters of reform said it’s more realistic to get rid of some superdelegates but not scuttle the system altogether.

Some Democrats argued that Republicans might have been well served by having superdelegates this year.

“They might have been able to prevent Trump. So I think that superdelegates play a big role,” said Sen. Tom Udall of New Mexico, who supports eliminating half the party’s superdelegates. “If Trump ends up being a disaster, [Republicans] are going to try to figure out … ‘How do we prevent this from happening [again]?’ And my guess is the way they will do it is come up with something like a superdelegate model.”

Another problem for those looking to kill the two-tiered system? Politicians usually stubbornly resist efforts to water down their own power.

“Asking a superdelegate to get rid of themselves?” asked Sen. Barbara Mikulski of Maryland, who wants a commission to examine party rules. “I would like to hear more from the grass roots than my colleagues on this.”

Plus, if superdelegates were eliminated, senators who wanted to attend the convention could be faced with the awkward situation of running for delegate slots against their own constituents. The CBC made that argument in letters to party leaders over the weekend, and several senators raised the specter of ugly jockeying for delegate slots.

“It’s complicated. Congress-people, do you want them at a convention? How do they get to a convention? Do you want them to run against somebody in the district?” asked Sen. Maria Cantwell of Washington, who is willing to entertain some reforms.

Some party officials are looking for a workaround. One option under discussion is binding superdelegates’ votes to the results in their state.

“Having party leaders participate is fine but I think having some connection to the outcome of your state’s process is smart,” said Kaine, a former Democratic National Committee chairman.

“It’s important that the elected officials [and] party leaders have an official role in the party conventions. I’m not as concerned about their votes affecting who the nominee is at our convention,” said Sen. Ben Cardin of Maryland.

The Sanders and Clinton campaigns declined to comment.

It’s unclear, though, whether Sanders and his supporters would accept a middle ground. Democratic Party officials in a number of states, including Wisconsin and Maine, have already taken votes in favor of scrapping superdelegates.

That could make it hard for progressives to accept a half-measure.

“We should get rid of superdelegates entirely,” said Sen. Jeff Merkley of Oregon, the only senator to endorse Sanders. “There are a tremendous number of delegates who feel like these superdelegate votes are fundamentally inconsistent with the soul of the Democratic Party.”