“Women like me aren’t supposed to run for office,” Alexandria Ocasio-Cortez says in her campaign video, but last night she proved that impression wrong. The 28-year-old left-wing activist defeated the Democratic dinosaur and 19-year incumbent Joe Crowley in New York’s primaries, taking pretty much everyone by surprise. In November she will almost certainly be elected to Congress to represent part of the New York districts of Queens and the Bronx.

“I wasn’t born to a wealthy or powerful family. Mother from Puerto Rico, Dad from the South Bronx. I was born in a place where your zip code determines your destiny,” she continues in her rousing video, which went viral.

Ocasio seemed stunned by her victory, too. A video shows the moment she hears the results. Her eyes widen, her hands fly to her mouth and she staggers backwards. “How are you feeling, can you put it into words?” an interviewer asks her, and she replies “no”. But she recovers her composure almost immediately.

Challenger @Ocasio2018 toppled one of the top Democrats in Congress, @repjoecrowley, Tuesday night in their primary in the 14th District. The victory stunned even her, live on our channel. #NY1Politics https://t.co/fnK1O0bacz pic.twitter.com/RjuqHJpn1p — Spectrum News NY1 (@NY1) June 27, 2018

“I cannot believe these numbers now but I do know that every single person here has worked their butt off to change the future for Bronx and Queens, that’s what I know,” she says, pointing to the people around her, her voice gathering strength. “This victory belongs to every single grassroots organiser, every working parent, every mom, every single member of the LGBT community, every single person is responsible.”

Ocasio-Cortez, a community organiser who until last year was working as a bartender to help pay the bills, worked for Bernie Sanders during his 2016 campaign. Her policy proposals include universal health insurance coverage, a federal jobs guarantee, free tuition at state universities and the abolition of Immigration and Customs Enforcement (ICE), the state body responsible for detaining and deporting undocumented immigrants.

Thesa all place her significantly to the left of the Democratic mainstream. Her victory will have shaken the party leadership and it will raise questions over the direction the party should be taking in the Trump era.

In recent weeks, Crowley spent hundreds of thousands of dollars on television ads and flyers. But Ocasio-Cortez landed several well-aimed personal blows against him, describing Crowley as the big money candidate who is out of touch with the working class, racially diverse districts he purports to represent.

“It’s time we acknowledge that not all Democrats are the same, that a Democrat who takes corporate money, profits from foreclosure, doesn’t live here, doesn’t send his kids to our schools, doesn’t drink our water, doesn’t breathe our air, cannot possibly represent us,” she says in her video. She characterised the race as people versus money: “we’ve got people, they’ve got money”.

Crowley was also damaged by his decision, ten days ago, to skip a debate with Ocasio-Cortez, sending a surrogate in his stead.

If and when she wins, Ocasio-Cortez will be the youngest woman ever to be elected to Congress. She is part of a new generation of Democrats – many of them women and from under-represented backgrounds – who have entered politics in response to the Trump administration. Mostly these candidates have had the backing of the party leadership, though there have been a few other surprises, such as the election in Nebraska of Kara Eastman, a 46-year-old social worker and progressive, who beat the former congressman Brad Ashford, the Democratic Congressional Campaign Committee favourite.

One thing is clear: this new wave may change the face of the party entirely.