Carlos Ramirez-Rosa’s smile grew ever wider as election results trickled in on Tuesday night.

By the time the 35th Ward Alderman took the stage at Rosanna Rodríguez-Sánchez’s election-night party at Chief O’Neill’s in Avondale, Chicago had experienced the biggest electoral victory for socialists in modern American history. Members of the group now control one-tenth of the City Council’s 50 seats.

“We know for certain that we have a five-member democratic socialist caucus in the Chicago City Council, and we’re so close to six,” Rosa told about a crowd of about 200 supporters. “You guys should be proud. No one thought we’d be at this point.”

Three members of the Democratic Socialists of America (DSA) won their runoff elections on Tuesday: Andre Vasquez (40th), Jeanette Taylor (20th) and Byron Sigcho-Lopez (25th). They join DSA members Rosa and newcomer Daniel LaSpata (1st), who won their council races outright in February.

Rodriguez-Sanchez (33rd) is narrowly leading Ald. Deb Mell by a few hundred votes, or less than 1 percent of the votes cast in a tight race that will likely be decided after the counting of mail-in ballots. If Rodríguez-Sánchez earns a City Council seat, it means that six socialists will ascend to power in city government.

“We won’t know if we’ll win for a few days, but no matter what happens we have several socialists who made it into City Council and we’re going to transform this city,” said Rodríguez-Sánchez.

Even with the 33rd Ward race still too close to call, five socialists is the most in Chicago since the 1910s, a decade in which the city was a hub of the radical left in America. Before the Red Scare of 1919, a dozen socialist newspapers were published in the city, and the city elected several aldermen who belonged to the Cook County Socialist Party, founded in 1896 as a response to the Pullman strike in Chicago.

Nearly a century after it declined in popularity, democratic socialism has enjoyed a significant boost by Bernie Sanders’ two presidential campaigns and the mercurial rise of DSA member and U.S. Rep. Alexandria Ocasio-Cortez. National membership in the group — which considers itself a “political and activist organization” but not an official political party — has multiplied by more than seven times since 2015, from 8,000 to 60,000.

“It helps that we have Bernie running and we have AOC popularizing our ideas on a national stage,” said local DSA co-chair Lucie Macías. “It’s a great time to be a democratic socialist in Chicago and the United States.”

It’s a great time to be a leftist in Chicago in general, said Emma Tai, executive director of United Working Families, a Chicago organization that endorsed three of the socialist candidates.

“If you weren’t paying attention, this left political uprising was surprising,” said Tai. “But this year was many years of struggle in the making. This year we saw things shift and all our organizing and contesting turned into real political power. I’m really proud of what we’re building together with this slate of City Council candidates.”

In terms of joining a caucus, some of the incoming class of councilman have advocated for moving the council’s progressive caucus to the left (“We could have a 12 or 15 member progressive caucus if we act strategically and with real discipline,” said LaSpata) while Rosa calls for a socialist caucus within the progressives.

“Rahm Emanuel said he was a progressive — it’s a label that is losing its meaning,” said Rosa. “Over the last several years, we’ve seen voters demand an alternative to the Democratic status quo, where we’re told that our public dollars need to go to projects like Lincoln Yards and millions in TIF funds to go to private pockets.”

“And so I think it’s incumbent on the democratic socialists to form a coalition in the City Council that fights for the redistribution of wealth, and moves the conversation to the left and fighting for the policies that are going to uplift the working class and improve our lives.”

Like many of Chicago’s 1,300 DSA members, many of the incoming council members are newcomers to the political nonprofit officially formed in 1982. LaSpata joined the DSA earlier this year while seeking the organization’s endorsement.

“I have been doing work that aligned with their values for years — before I knew what democratic socialism was,” he said. “For me, it was finding an organization that aligned with my values, I just didn’t know it was called democratic socialism.”

Taylor, a longtime activist and community organizer on the South Side who participated in a 34-day hunger strike to protest the closing of Dyett High School in 2015, only joined the organization in March, after she made it into the runoff.

“They’ve been on the right track on the issues but it’s important that they hear from everyday people impacted by these policies, from people who are hungry in the richest country in the world, who struggle to pay their rent,” said Taylor, who won the race in the 20th Ward with 60 percent of the vote. “I am looking forward to building a coalition of the many.”

Rodriguez-Sanchez has been compared to Ocasio-Cortez in the past because she’s a Latina socialist with Puerto Rican roots running against a powerful incumbent. Her campaign is an attempt to disrupt a ward ruled by the Mell family dynasty since 1975 — first by Dick Mell, former Gov. Rod Blagojevich’s father-in-law. Mayor Rahm Emanuel appointed Mell’s daughter, former state representative Deb Mell, as his replacement in 2013.

But not without some controversy. Last weekend, Mell’s campaign posted a photo of one of Rodriguez-Sanchez’s volunteers on Facebook along with a screenshot of one of his previous posts that proclaimed that “the goal of socialism is communism.”

“This isn’t Bernie Sanders. This isn’t Alexandria Ocasio-Cortez. This is something very different altogether and Rossana’s campaign doesn’t seem to mind putting it out there for everyone to read,” read the post. “Residents expect an alderman to put aside ideology and get things done, not peddle some radical political agenda.”

Macías called Mell campaign’s post “irresponsible red-baiting.”

“It just shows that democratic socialist principles and what we stand for are popular with people,” she said. “These machine candidates are not really providing an alternative so all they can do is attack.”

But with the election now over, the socialists will soon have new battles to fight inside council chambers. Rosa is hopeful that mayor-elect Lori Lightfoot will be supportive of a more independent-minded council.

“We’ll see. A lot of my colleagues, all they know how to be is a rubber stamp for the mayor,” he said. “At the end of the day I know I have at least four additional candidates — hopefully five — plus someone like [newly elected aldermen] Matt Marton or Maria Haddon that will continue to move the conversation to the left and fight for a more progressive City Council.”