Supporters of Vermont Sen. Bernie Sanders Bernie SandersSirota reacts to report of harassment, doxing by Harris supporters Republicans not immune to the malady that hobbled Democrats The Hill's Morning Report - Sponsored by Facebook - Republicans lawmakers rebuke Trump on election MORE’s (I) presidential campaign are crying foul over the Working Families Party’s (WFP) endorsement of Sen. Elizabeth Warren Elizabeth WarrenOvernight Defense: Appeals court revives House lawsuit against military funding for border wall | Dems push for limits on transferring military gear to police | Lawmakers ask for IG probe into Pentagon's use of COVID-19 funds On The Money: Half of states deplete funds for Trump's 0 unemployment expansion | EU appealing ruling in Apple tax case | House Democrats include more aid for airlines in coronavirus package Warren, Khanna request IG investigation into Pentagon's use of coronavirus funds MORE (D-Mass.).

Warren won the group’s endorsement on Monday after a vote by the WFP’s national committee, which includes representatives from state and local WFP chapters, and a separate vote of WFP members and grassroots supporters.

ADVERTISEMENT

WFP spokesman Rob Duffey told The Hill that Warren won 60.9 percent of the ranked-choice vote. The two votes by the national committee and the group's members and grassroots supporters were weighted equally.

But the progressive, union-allied group declined to release the vote breakdown.

"The final result is the only number we ever planned to release," Duffey said. "It represents the inputs from all the constituencies that make up the WFP."

Duffey said a WFP member is anyone who pays dues of $10 per month or $120 in the past year, and that a WFP supporter is anyone who has previously engaged with the group and signed up for the WFP's email or text list.

The New York Times reported that 56 people sit on the WFP national committee. According to Duffey, each vote is a delegate casting a vote on behalf of their state chapter or local branch.

The endorsement was notable in that Sanders won the group’s support in the 2016 primary against former Secretary of State Hillary Clinton Hillary Diane Rodham ClintonBloomberg rolls out M ad buy to boost Biden in Florida Hillicon Valley: Productivity, fatigue, cybersecurity emerge as top concerns amid pandemic | Facebook critics launch alternative oversight board | Google to temporarily bar election ads after polls close Trump pledges to make Juneteenth a federal holiday, designate KKK a terrorist group in pitch to Black voters MORE, who went on to become the Democratic presidential nominee.

Some prominent backers of Sanders have loudly protested the latest endorsement.

Two top editors of socialist magazine Jacobin wrote an article Tuesday titled “The Working Families Party Has Written Itself Out of History.”

“If the WFP views bottom-up organizing, of and by a multiracial working class, as a core necessity to win social change, why would the party endorse Warren, whose campaign has catalyzed neither — especially over Sanders, whose campaign has?” the magazine’s founder and managing editor wrote.

They also speculated that the organization has “something to hide,” writing that “members were likely divided between Warren and Sanders.”

The Sanders campaign, however, has not criticized the group or the result.

“We look forward to working with the Working Families Party and other allies to defeat Donald Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE,” campaign manager Faiz Shakir told The Hill in a statement. “Together, we’ll build a movement across the country to transform our economy to finally work for the working class of this country.”

Duffey said WFP's process "included both representative democracy and direct democracy, and we were clear about this from the start. We're proud of it."

Sanders and Warren are both battling with former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE and more than a dozen other candidates for the Democratic nomination.

Biden, Sanders and Warren are widely seen as the three leading candidates.

Sanders and Warren have avoided direct criticism of one another for most of the campaign, even as they battle for progressive support in the Democratic Party.

Updated at 1:55 p.m.