On Tuesday night, a 28-year-old political newcomer and self-described socialist, Alexandria Ocasio-Cortez, defeated one of the most powerful and entrenched Democrats in Congress in a New York primary.

Rep. Joe Crowley, a 56-year-old Irish-American who has long ruled the Queens Democratic machine, represented the party establishment, while Ocasio-Cortez galvanized the insurgent left wing.

In one of the most diverse districts in the country, Ocasio-Cortez ran on a deeply progressive platform, calling for Medicare for all, a federal jobs guarantee, and immigrant rights.

On Tuesday night in New York, a 28-year-old political newcomer and self-described socialist, Alexandria Ocasio-Cortez, defeated one of the most powerful and entrenched Democrats in Congress in a shocking primary win for the progressive wing of the party.

Ocasio-Cortez is likely to be the youngest woman ever elected to Congress come November.

In his concession speech, Rep. Joe Crowley appeared to acknowledge the broader movement Ocasio-Cortez is a part of — a younger generation of more progressive and anti-establishment Democrats, many of whom put their faith in Sen. Bernie Sanders' insurgent 2016 presidential campaign.

"It's not about me; it's about America," Crowley, the 10-term incumbent, told his supporters. "I want nothing but the best for Ms. Ocasio-Cortez."

A reaction to Trump and the Democratic establishment

New York City is one of the most vibrant hotbeds of the Democratic "Resistance." And New York's 14th Congressional District, which includes parts of the Bronx and Queens, is home to many of the communities feeling most at risk under President Donald Trump.

Crowley, a 56-year-old Irish-American, has represented the district for 20 years and long reigned as the leader of the Queens Democratic machine. With deep ties to the party establishment in New York and Washington, Crowley had faced a primary challenger only once, in 2004.

A young Latina with a mother from Puerto Rico and a father from the Bronx, Ocasio-Cortez is a product of her Queens-Bronx district, which includes some of the most diverse neighborhoods in the country and possibly the world.

"NYC is home to millions of immigrants, and millions of others whose families fled the Nazis, the terror of the American south, or persecution elsewhere," the New York Times editorial writer Mara Gay tweeted Wednesday. "The city is deeply anxious, angry and sad about what is happening in the country. That is the context for yesterday's election."

A relatable story

Democrats say Ocasio-Cortez was able to speak both to and for her district, where she was raised by a Puerto Rican mother and Bronx-born father, in a way that was both authentic and compelling. Her personal story, as a political activist who made ends meet with service industry jobs, made her relatable, and her clear, bold platform made her inspirational.

"She was able to project extraordinary charisma," said Jon Reinish, a Democratic strategist and former aide to New York Sen. Kirsten Gillibrand. "Democrats win when they are able to create a movement behind themselves and she did exactly that."

Reinish added that Ocasio-Cortez's message that women like her "aren't supposed to win," but that she wouldn't let anyone stop her, was particularly powerful.

"She told a story that thousands of people across her district said, 'Oh my god, that’s me,'" Reinish said.

A socialist platform

Ocasio-Cortez ran on a deeply progressive platform, focusing her message on reducing inequality and expanding opportunity for poor and working-class New Yorkers.

Pointing to the rising economic inequality and pervasive poverty in New York City, Ocasio-Cortez is calling for Medicare for all, a federal jobs guarantee, and affordable housing, among other demands.

Setting her apart from most Democratic candidates and lawmakers is a call to abolish Immigration and Customs Enforcement, the agency tasked with deporting undocumented immigrants that's increasingly a target of left-wing ire.

Sean McElwee, a progressive activist and pollster who has helped popularize a movement to abolish ICE, said Ocasio-Cortez would raise the effort's profile to new heights.

"Ocasio-Cortez has the most comprehensive vision of a world without ICE of any candidate in the country," McElwee told Business Insider. "Her opponent voted to establish ICE. She promised to abolish it and investigate its abuses. At the end of the day, voters made their choice, overwhelmingly."

A banner for Ocasio-Cortez's campaign. Scott Heins/Getty Images

Ocasio-Cortez also rejected corporate donations. A whopping 70% of her campaign donations were under $200, compared with 0.78% of Crowley's.

And while Crowley raised nearly $3 million for his reelection campaign — and spent about $1 million — his challenger raised just $600,000.

"Americans want a leader who's going to take a battle ax to the system and upend it," Anne Feldman, the press secretary for End Citizens United, a group advocating campaign-finance reform, told Business Insider. "Candidates who reject corporate PAC money are tapping into that sentiment and showing — not telling — voters that they'll make a difference, and that's leading to success at the polls."

Ocasio-Cortez, who was an organizer for Sanders during his presidential campaign, thanked her supporters late Tuesday.

"This is the start of a movement," she tweeted. "Thank you all."

'Doors that had never been knocked on before'

Democratic strategists — and Ocasio-Cortez herself — attribute much of her victory to her aggressive door-to-door ground campaign.

"We won because, I think, we had a very clear winning message, and we took that message to doors that had never been knocked on before," Ocasio-Cortez told CNN on Wednesday morning.

Just 27,658 people voted in the primary on Tuesday (with 98% of precincts reporting) in a district with over 214,000 registered Democratic voters, as of April 2016. By all accounts, Ocasio-Cortez's grassroots-fueled campaign spent months flooding the streets, knocking on doors, and hanging signs.

Meanwhile, Crowley, who lives in Washington, sent a surrogate to one debate to take on Ocasio-Cortez in his place.