On Monday night, Senator Bernie Sanders of Vermont tested out his “radical idea”—a vision of American democratic socialism—with real American voters in Iowa. Numerically, the race was a dead heat, with Clinton barely inching ahead of Sanders. It was not, in other words, the kind of explosive surge that might produce its own groundswell of enthusiasm, a victory begetting more victories. But for a candidate who had been expected to be a non-threatening bit-player in the Democratic primary, the achievement was enormous. And for Americans hoping to see a way forward for democratic socialism on their home turf, it was even bigger.

“I think it’s overwhelmingly positive,” David Duhalde, deputy director of Democratic Socialists of America, told the New Republic of Sanders’s performance. “People were pleasantly surprised at how well Bernie did. I think just the tie is a victory in itself, and it just shows how much he overcame with pretty much just volunteers, a handful of union endorsements, and a really, really good message that really resonated with people.”

Democratic Socialists of America is the largest socialist organization in the United States, and has been pushing to “establish an openly democratic socialist presence in American communities and politics” since 1982. But Americans who identify with the broad category of socialism have faced an uphill battle over the last several decades. Since the Cold War, socialism has been a dirty word in American politics, used more often to smear public figures like Barack Obama and Pope Francis than to identify a real set of political values and programs. A 2015 Gallup poll found that 50 percent of Americans would have a hard time voting for a self-proclaimed socialist presidential candidate, the highest rate of disapproval in a slate of hypothetical candidate identities that included Jewish, gay or lesbian, a woman, black, and atheist.

But Sanders’s candidacy has shifted the public perception of socialism—at least notional socialism—somewhat. “He’s made it easier to identify as a socialist, and for people to organize as socialists,” Duhalde said. “Our new membership rates have doubled since he’s been running. So people are willing not just to identify as socialists, but to actually make that financial commitment.”

Part of Sanders’s success campaigning under the socialist banner likely arises from the base he has managed to reach: namely younger, further-left, and lower-income voters. Exit polls from Monday night’s Iowa caucuses found that Sanders won 84 percent of voters between the ages of 17 and 29, 58 percent of voters who identified as “very liberal,” and 57 percent of those making under $30,000 per year. Sanders pulled in half of those making between $30,000 and $49,000 per year, losing his lead over Clinton only as the income bracket shifted upward: Clinton took 55 percent of the $100,000 and over category, with Sanders trailing at 37 percent.