Rep. Adriano Espaillat, D-N.Y., has lost his primary to a challenger backed by New York Mayor Zohran Mamdani, NBC News projects, in a major victory for the progressive wing of the Democratic Party.Community organizer and activist Darializa Avila Chevalier, a 32-year-old member of the Democratic Socialists of America, defeated Espaillat, 71, after having cast him as an insufficient fighter for the working-class residents of the upper Manhattan district who was out of step with Democratic primary voters on Israel policy. “Where is our congressman when ICE is kidnapping his constituents? Why should we let Adriano Espaillat vote to spend billions on bombs overseas when we’re struggling to afford rent and groceries right here in New York City?” Avila Chevalier, who works at a public defender’s office, said in a video launching her campaign. “We live in the richest country in the history of the world. It’s never been that our government lacks the resources to help us. It’s just that the establishment lacks the courage,” she continued. She had support on the airwaves from Justice Democrats, which backs progressives taking on Democratic incumbents. But she also faced an onslaught of attacks from groups backing Espaillat, including allies of the Hispanic Caucus, which Espaillat chairs. The attacks highlighted her past social media posts, in which she profanely criticized Democratic leaders, including calling former President Joe Biden a “rapist” and writing “F--- Kamala Harris.”The posts, according to reports from the New York Post and CNN, also included comments that “Israel doesn’t exist,” that “a world without prisons or police” is needed and that “all deportation is wrong.” Avila Chevalier told NBC News this month that now that she is older she is “understanding a little more how a lot of these systems function.”“My values have always been my values,” she said. “But my understanding of how to approach the systems has grown.”She also responded with a TV ad saying: “The same billionaires that attacked Zohran Mamdani are now spending millions against me. They know that unlike Adriano Espaillat, I can’t be bought and I won’t back down to Trump.” Avila Chevalier’s campaign in the 13th District had mostly flown under the radar both nationally and in New York City until Mamdani endorsed her last month, despite having initially promised to back Espaillat. He stood by her after those posts emerged.Rep. Adriano Espaillat, D-N.Y., walks through the Capitol in February.Heather Diehl / Getty Images fileEspaillat endorsed former Gov. Andrew Cuomo in last year’s mayoral primary but backed Mamdani after he won the nomination. Mamdani then privately promised to support him, a pledge first reported by The New York Times and Politico and confirmed by a person familiar with the conversation, before he eventually reneged and backed Espaillat’s challenger. Mamdani’s campaign did not comment on any agreement. Mamdani cast Avila Chevalier as the future of the Democratic Party, saying as he announced his endorsement on MS NOW that she will be “on the front lines” of showing that Democrats “have to be fighting for a vision that reckons with the fact that working people were not left behind just four years ago or 16 years ago. They were left behind a long time before that.”“And it will take a new generation of leadership to ensure that the heartbeat of this party is once again the struggles of the working class,” Mamdani said. Avila Chevalier is also a vocal critic of Israel, calling its war against Hamas in Gaza a genocide. A Columbia University alumna, she participated in the pro-Palestinian protests at the university and was present during last year’s standoff with police at Hamilton Hall, which she described as “quite horrific.” She also attended a controversial pro-Palestinian rally the day after Hamas’ 2023 attacks in Israel — an event that Brad Lander, the former city comptroller also sporting Mamdani’s endorsement in his congressional bid, condemned. Avila Chevalier has voiced support for legislation to block certain arms sales to Israel, also known as the “Block the Bombs” bill. She has also called for abolishing ICE, “Medicare for All” and national tenant protections.Espaillat leaned into his experience pushing for affordable housing and immigrant rights. He was the first former undocumented immigrant, and the first Dominican American, elected to the House. “I’m running on my record, a record of accomplishment, a record that has listened to people and that has brought back results to the community I represent,” he said at a Spectrum News NY1 debate.Espaillat had support from House Minority Leader Hakeem Jeffries, Gov. Kathy Hochul, state Attorney General Letitia James, City Council Speaker Julie Menin, the Congressional Black Caucus and the state AFL-CIO. The race had turned negative in its final days, with Avila Chevalier, an Afro-Latina who is Muslim, accusing Espaillat and his supporters of racist attacks and “lies about my identity, my faith and my family.” Avila Chevalier said in a video on social media that Espaillat’s supporters have been “standing at poll sites in our district shouting lines and slinging racial slurs.” She said that “I have been hit with attacks that use Haitian as a slur” and that people have reached out to her family demanding to see her birth certificate. Espaillat told The City Reporter: “I condemn — the campaign has been very aggressive. I ask for people to tone it down.”