After the results were announced, angry Ellison loyalists rose from their seats in the back of the ballroom at the Westin Peachtree Plaza Hotel and tried to shout down outgoing interim chair Donna Brazile, chanting, "Party for the people, not big money!"
"This shows that the Democratic Party didn't learn their lesson," said Alexa Vaca, an Ellison backer and supporter of Vermont Sen. Bernie Sanders during the party's divisive 2016 primary race. "They are not going to be in touch with the people and they are not ready to move in a new direction despite the rhetoric."
The race for Democratic National Committee chair, normally a quiet affair managed by party insiders, emerged as a roiling public campaign, as progressives loyal to Sen. Bernie Sanders and establishment Democrats jousted for control of a depleted organization increasingly at loose ends after eight years in the White House and then Hillary Clinton's unexpected loss to Donald Trump.
In the run-up to the vote, both candidates had liberal luminaries making calls to members on their behalf. Sanders and New York City Mayor Bill de Blasio, who spent the last two days in Atlanta, actively stumped for Ellison. On Perez's side, former Vice President Joe Biden and longtime Obama confidant and adviser Valerie Jarrett worked the phones.
Perez came up a vote short of a clinching majority on the first ballot, then captured 235 of the 435 votes cast on the second. In between votes, the Ellison camp sent out a text message to DNC members claiming that South Bend, Indiana, Mayor Pete Buttigieg, who dropped out of the running before a vote was cast, had endorsed him.
But the information was incorrect, and Buttigieg confronted Ellison backstage. A correction was sent out with an apology.
Still, after winning, Perez quickly moved to bring Ellison's supporters into the fold by appointing Ellison as the DNC's deputy chair, saying later that he and his new deputy had discussed giving the loser that spot "for some time."
Still, Ellison supporters questioned a process that put the chair in the hands of only several hundred people.
"The way the rules are set up is a big structural impediment to the DNC being fully in touch with this moment or any other moment," Adam Green, co-founder of the Progressive Change Campaign Committee, told CNN. "The winds of change cannot quickly come through the DNC. Maybe that's intentional."
National Nurses United Co-president Jean Ross, whose organization was the first national union to endorse Sanders in 2015, said she was "bitterly disappointed" by the result and accused Ellison's opponents of running a "smear campaign" against him.
"Those of in labor know power never concedes. Never," she said. "No, you have to take it from them. And they're not ready. They're going to fight us tooth and nail."
Ellison and Perez enjoy a friendly relationship, but their respective supporters clashed throughout the months-long process, which included a series of "future forums" around the country and a national debate on CNN.
Before the Saturday vote, Larry Cohen, the board chair for Our Revolution, a progressive group spawned by Bernie Sanders' primary campaign, railed against a Friday afternoon email from the American Jewish Congress that said the election of Ellison, who is Muslim, could "threaten the relationship between America and our ally Israel."
"That was a disgrace," said a visibly irritated Cohen, who formerly headed the Communications Workers of America. "I would have liked to see Tom Perez repudiate that letter. But he didn't do a thing about it."
More grumbling followed Brazile's announcement that plans to use an electronic voting system would be scrapped in favor of paper ballots because of slow convention center Wi-Fi. Ellison supporters — still suspicious after what many consider a "rigged" presidential primary fight -- fretted that the candidate would not be able to view, in accordance with party bylaws, the names of potentially persuadable members after a first ballot.
After a contest in which the two frontrunners repeatedly sought to downplay divisions within the party, the finale recalled the contentious 2016 primary fight, which saw Florida Rep. Debbie Wasserman Schultz resign from the chair in late July after hacked emails appeared to show DNC officials favoring eventual nominee Hillary Clinton.
The hard feelings lingered for months, and at least among stalwart Sanders voters and some progressive groups, the DNC race was viewed as a second chance at wresting control of the party from its establishment elders.
"The leaders of the Democratic Party missed an opportunity today," Dan Cantor, national director of the Working Families Party, said in a statement. "This vote may sting for progressives, particularly young people."
Ellison, who agreed to come on as deputy party chair, later asked his backers to stick with party.
"If they trust me, they need to come on and trust Tom Perez too," Ellison said of his vocal supporters.
We Will Replace You, a progressive group dedicated to seeding primary challenges against elected officials who fail to take a hard line against the Trump administration, said Ellison's defeat marked a failure in the party's efforts to coalesce the anti-Trump protest movement into a winning electoral coalition.
"The biggest question facing the Democratic Party establishment now is whether they will join the grassroots resistance against Trump," co-founder Waleed Shahid said. "While we wait for their answer, the American people are going to continue leading the fight in the streets and at the ballot box."