If America’s democratic socialists learned anything from watching Bernie Sanders’ deep run in the Democratic primary last year, it’s that they don’t have to be losers anymore.

Inspired by the Vermont senator’s success at forcing left-wing ideas into the nomination battle, the nation’s largest socialist organization, the Democratic Socialists of America, has watched its dues-paying membership, which historically has hovered around 5,000, swell to 29,000. The DSA is still nowhere near the levels of the Socialist Party in 1920, when nearly a million people voted for Eugene Debs, but its members, too young to remember the Cold War, much less the “red scares” of the 1910s and 1950s, aren’t content to sit quietly on the political sidelines, perennially irrelevant in a system built to sustain two major parties.

They want to win. And to do it, socialists are dispensing with their penchant for symbolic protest votes and their principled disdain for an electoral process they believe can’t deliver meaningful change. Sanders’ ability to run well in primaries across the country, say new DSA members, proved that democratic socialism isn’t destined for the kind of third-party tokenism that bedevils the Green Party and World Workers Party, among others. And it has opened their minds to an electoral strategy that was until very recently considered heretical.

“The only viable electoral strategy is to work with the Democratic Party,” says Michael Kazin, the editor of leftist magazine Dissent. “There is no viable third party.”

The consequence of this willingness to play in the main arena is that a loose confederacy of splinter groups—socialists, anarchists, communists and leftists, all spearheaded by the DSA—are more willing than ever to sacrifice ideological purity for a chance to work as an insurgent coalition inside the Democratic Party. The DSA leadership insists that it feels no loyalty to the Democratic National Committee, but it is eager to challenge Democrats on their own turf.

“Absolutely, we definitely want to primary neoliberal Democrats,” says Maria Svart, the DSA’s national director, who, like others in the DSA, uses the epithet “neoliberal” to paint moderate Democrats as insufficiently progressive. “What we’re trying to do is build an organized grass-roots constituency for democratic socialism, and the politicians we’ll support are the ones who can win.”

Of course, when it comes to throwing electoral weight around, 29,000 members collectively don’t make much of an impact. But that doesn’t discourage the group, which points to a surprising precedent as proof that it can punch above its weight class. In April 2010, the Tea Party claimed just 67,000 members, and yet it still managed to win 47 seats in the House of Representatives that November. That’s because millions more Americans supported the Tea Party movement without signing up, and voted for Tea Party-affiliated candidates running as Republicans. By positioning themselves as the natural heirs of Sanders’ 2016 campaign, the DSA leadership thinks it can claim the allegiance of Americans who might not want to pay its membership fees but nevertheless support the ideas of democratic socialism.

Whether Democrats need this kind of progressive shot in the arm is a matter of debate within the party. But there’s not a lot of enthusiasm for the party to play host to a Tea Party-like parasite.

“The country is an overwhelmingly moderate country looking to see its political system pull away from extremism,” says Mark Penn, a former pollster and adviser to both Bill and Hillary Clinton. Penn warns that competitive primaries should help build the party rather than tear it apart. “Are they splintering the Democrat vote or are they adding to it?”

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The evolution of the Democratic Socialists began almost as soon as Hillary Clinton sewed up the nomination. Sanders does not affiliate itself with the DSA, but the DSA actively supported Sanders’ bid for the Democratic nomination. Once the Sanders campaign dissolved, the DSA became a landing ground for former volunteers in Bernie’s campaign, many of whom were registered Democrats.

“I already considered myself a socialist,” says Amy Zachmeyer, now co-chair of the DSA’s Houston chapter, “but didn’t realize there were so many of us until Bernie Sanders kind of made it OK to talk about being a democratic socialist.”

By signaling its willingness to compete within the Democratic Party, the DSA has attracted more than just out-of-work Bernie staffers. Even incumbent Democrats look at it with new interest. Carlos Ramirez-Rosa, a Chicago alderman and member of the Democratic Party who joined the DSA last year, says he joined DSA once he recognized the organization had begun to embrace a kind of democratic socialist realpolitik.

“While they had the right analysis, they had the right values, [they] were not necessarily engaging in the electoral arena in a way that I thought was necessary if the left was going to win,” says Rosa. But starting last year, he “began to see a DSA that was much more focused on being a disciplined force to help elect leftists.”

Rosa is not alone: khalid kamau, a city councilman in South Fulton, Georgia; Mike Sylvester, a state legislator in Maine; and Nirva LaFortune, a city councilwoman in Providence, Rhode Island, are among the elected Democrats who’ve joined the DSA.

And although it took the rise of a 76-year-old independent senator from Vermont to normalize socialism within Democratic Party politics, it was another event that kicked the DSA into high gear: the election of Donald J. Trump.

“If you look at our growth in membership, our big surges have been after big announcements by this administration,” says Margaret McLaughlin, the chair of Washington, D.C.’s, DSA chapter. “Like the Muslim ban, DACA. Charlottesville was huge.”

DSA leaders hope their bolstered roster and influx of new funds—along with the continued specter of the man in the Oval Office—will help position the organization to challenge the Democratic Party from the left. Currently, there are 25 DSA members running for office—from Seattle to Lakewood, Ohio, to New York City—and the group expects to endorse a larger wave of candidates for the 2018 midterms.

One of the DSA’s members running for office this November is Lee Carter, a former U.S. Marine and self-described socialist who is challenging the GOP whip in Virginia’s state House. In Carter’s district, Clinton beat Trump by nearly 13 percent. And yet, Carter says he has received little support from Virginia’s Democratic Party. “The state party’s resources are stretched thin,” he explains.

But the local chapter of the DSA has made Carter’s race a priority. Once it endorsed his campaign, the group started mobilizing its members to canvas Carter’s district on his behalf. “We’ve managed to knock on tens of thousands of doors,” says Carter.

DSA leadership insists that it isn’t interested in backing only Democrats like Carter. In New York City, the DSA endorsed Jabari Brisport, a Green Party candidate for city council running in a district that is so liberal he actually has a shot at victory.

“We as an organization are not interested in campaigns which are purely symbolic. We are here to win elections,” says Daniel Moraff, a member of the DSA’s election committee. And if their candidate doesn’t win, many DSA members would rather vote for what they see as the lesser of two evils, rather than vote for a protest candidate.

“Most people I know that are in DSA fought really, really hard for Bernie, and then voted for Hillary,” says McLaughlin, when asked whether many DSA members voted for Jill Stein in 2016. “Most if not all voted for Hillary in the general election.”

Democrats in the moderate and progressive wings of the party are glad to hear that young socialists would rather vote for a Democrat than a noncompetitive third party. But the prospect of a progressive Tea Party, challenging incumbent Democrats and dragging the party to the left, sounds like a disaster to some moderates.

“If the democratic socialists were able to take over the Democratic Party, I think it would become a minority party for the next 10 to 20 years,” says Lanae Erickson Hatalsky, vice president at Third Way, a think tank that advocates the centrist politics championed by Bill Clinton and Tony Blair. Hatalsky authored a report on the perils of leftist populism, based on focus groups with voters who backed both Barack Obama and Donald Trump. These voters see the Democratic Party as anti-business, the report found, and Democratic proposals branded as “handouts” only exacerbate that resentment.

“I don’t think many Democrats would consider themselves socialists,” says former DNC chair Donald Fowler, who has called for Sanders to officially join the party. “I think if people want to be Democrats, they should come into our party and be a part of it.”

Other Democrats welcome a grass-roots movement that can keep incumbents on their toes.

“The democratic socialists I’ve met are constructive people; they want to get things done,” says former Vermont Governor Howard Dean, who ran for president from what he called the “democratic wing of the Democratic Party” in 2004. “The DNC is going to be essentially supplanted by whatever institution younger people prefer.”

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No matter how much Sanders managed to bring democratic socialists into the mainstream, there’s still a taint to the socialist identity that will make its emergence a challenge for a long time.

In September, Alderman Carlos Ramirez-Rosa’s association with the DSA contributed to his expulsion from a gubernatorial ticket in Illinois. State Senator Daniel Biss, who is running for governor, had announced Rosa as his choice for lieutenant governor the week before. But when it was revealed that the DSA had endorsed a pro-Palestinian boycott of Israeli goods, and that Rosa supported the decision, Biss quickly dumped Rosa amid criticism and the DSA lost its highest-profile candidate to date.

Rosa argues that opinions on Israel are changing—liberal millennials have become less sympathetic toward Israel over the past decade, according to a 2016 Pew Research Center Poll. And while that may be true, the country as a whole still overwhelmingly supports Israel over Palestine.

There is also the shadow of the “Bernie Bro” to reckon with—the perception that Sanders supporters are mostly white, male leftists who care more about economic inequality than racial justice and gender equality. The mere mention of the label makes many DSA members bristle.

“You see a lot of women really out there doing the work. You see a lot of women who are in leadership positions,” says Zachmeyer of the DSA. “When people make this argument that we’re really a bunch of Bernie Bros, they’re really erasing women.”

DSA leadership contends that it reserves at least half of the slots on its National Political Committee for women, and each chapter is supposed to have a female co-chair.

The endorsements of candidates of color, like Rosa and Jabari, are also part of a concerted effort to diversify traditional leftist bases of support. In the DSA’s 2017 strategy document, the organization admits it has a problem: “Organizations of the Left (including DSA) generally reflect the interests, aspirations, and cultural assumption of white working- and middle class individuals more than people of color.”

Even if the DSA can cobble together the coalition it aspires to, the group still faces long odds in taking on a Democratic establishment still wary of the label “socialist.” House Democratic leader Nancy Pelosi drew a line in the sand at a CNN town hall earlier this year when asked about growing anti-capitalist tendencies among young voters. "We're capitalists, and that's just the way it is," Pelosi said.

But that’s not how DSA members see it. And if they can continue what the Sanders’ campaign started, someday that might not be the way the way leading Democrats see it either.