It’s all captured on tape: the moment Alexandria Ocasio-Cortez, the 28-year-old Bronx-raised democratic socialist running to represent New York’s 14th District, looks up at a TV screen and realizes she’s beaten out Joe Crowley, the 19-year incumbent and chairman of the House Democratic Caucus. She’s just walked into Park Billiards Cafe & Sports Bar, the Bronx taproom where her organizers were watching the results roll in, and is speaking to a reporter from local TV station New York 1. Her eyes widen in shock and she claps her hands over her mouth, lowering them seconds later to reveal an elated smile. “I cannot believe these numbers right now, but I do know that every single person here has worked their butt off,” she says, looking around her. “This victory belongs to every single grassroots organizer, every parent, every mom, every member of the L.G.B.T.Q. community. Every single person is responsible for this.”

By now the video has gone viral, and so has Ocasio-Cortez, whose campaign was supported by gubernatorial candidate Cynthia Nixon, MoveOn, the Bernie Sanders–affiliated Our Revolution, and Howard Dean’s Democracy for America. The former Sanders organizer, who was a bartender as recently as last November, argued that it was past time for someone like her, a young Puerto Rican woman from the Bronx, to represent an overwhelmingly nonwhite district. She was outspent 10-to-1, spending just $128,140 from the beginning of April to June 6, compared to Crowley’s $1.1 million over the same period. “We have basically, on one side, a multimillion-dollar machine candidate that was never elected, who does not live in the district—he lives in Virginia, his children go to public school in Virginia,” Ocasio-Cortez told the Queens Courier of her opponent. “It’s really kind of the pinnacle of someone who is a little out of touch but very influential.”

Ocasio-Cortez clinched her victory, her supporters say, by seizing on dissatisfaction with the New York Democratic establishment, seeking out the votes of those who tend to go ignored by the Democratic Party. Though Crowley was a reliable Democratic vote in Congress, Ocasio-Cortez is to his left politically, a member of the Democratic Socialists of America who ran on a platform that included “Medicare for All” and a federal jobs guarantee. She supported abolishing ICE months before congressional Democrats began to do so. “I was stunned that she won but I shouldn’t have been,” one volunteer Democratic Socialists of America organizer who worked for months on Ocasio-Cortez’s campaign told me. “I was on the ground, seeing the enthusiasm for her.”

In the grand scheme of the Democratic Party, Ocasio-Cortez’s win is a massive upset—Crowley was seen by many as a favorite to succeed House leader Nancy Pelosi should she opt to step down. Some have likened her victory to an Eric Cantor moment, a reference to the former House majority leader who lost a 2014 primary to a virtually unknown opponent. Crowley’s loss may very well plunge the contest for House leader into chaos, spurring other contenders to declare their interest in the role—after all, as Politico’s Heather Caygle points out, it’s incredibly rare for a leadership slot to open up without a clear successor.

Though Ocasio-Cortez’s victory undoubtedly shows that hard-left candidates can take on long-entrenched establishment figures and win, there’s some debate as to whether it’s indicative of a nationwide, young, progressive wave. New York’s 14th District covers northwest Queens and a piece of the Bronx; it leans lopsidedly Democratic and is majority-minority. “Sanders-style candidates are still losing almost all of the Democratic primaries they run in,” Matt Bennett, of center-left group Third Way, told Axios. “If Democrats do regain control of the House . . . it will be largely because of moderates winning in tough red and purple districts.” Victories like Ocasio-Cortez’s, however, will undoubtedly shape the messaging Democrats use to target those districts. “For decades, safe Democrats treated their seats like lifetime appointments and haven’t moved to match the progressivism of the base,” writer and activist Sean McElwee told me. “Despite representing among the most diverse and immigrant districts in the country, Crowley voted to establish ICE . . . Ocasio-Cortez promised to abolish it. Voters made their choice.” The D.S.A. volunteer echoed his sentiments. “What we saw in Pennsylvania with the D.S.A. win there, and what we saw in this race, is that people who want to elect women and women of color are not scared off by left demands,” the volunteer said. “There are a lot of people who want to elect progressive women, and they’re not afraid of calling for single-payer health care or abolishing ICE. That’s a narrative being pushed by people who have a vested interest in protecting the donor class.”

Ocasio-Cortez herself drove this message home in a highly acclaimed campaign video last month. “It’s time we acknowledge that not all Democrats are the same,” she said. “That a Democrat who takes corporate money, profits off foreclosure, doesn’t live here, doesn’t send his kids to our schools, doesn’t drink our water or breathe our air cannot possibly represent us.” (The Hive has reached out to Crowley’s campaign for comment on Ocasio-Cortez’s allegations.)

“Women like me aren’t supposed to run for office,” she added. But come November, after a general election that seems more like a formality than a challenge, she will likely be sworn in as the youngest congresswoman in history.