New York Mayor Zohran Mamdani’s progressive allies delivered a major shake-up in Tuesday’s Democratic congressional primaries, defeating two sitting House members and strengthening the democratic socialist leader’s push to reshape the party’s future.The biggest upsets came in New York City, where Mamdani-backed candidates toppled longtime incumbents and sent a warning shot to the Democratic establishment ahead of November’s midterm elections.Darializa Avila Chevalier, a democratic socialist endorsed by Mamdani, defeated Rep. Adriano Espaillat, a five-term incumbent and chair of the Congressional Hispanic Caucus. Avila Chevalier, 32, gained attention for organizing pro-Palestinian demonstrations at Columbia University and for running as an outsider, challenging what she called the “Democratic machine.”Rep. Dan Goldman, a two-term congressman and heir to a prominent political family, was also defeated by former New York City Comptroller Brad Lander, a progressive closely aligned with Mamdani’s movement.Mayor Zohran Mamdani speaks during a Primary Night watch party for NYC Congressional Candidate Claire Valdez at 99 Scott Studio on June 23, 2026, in the East Williamsburg neighborhood of Brooklyn (Getty)Mamdani ally Claire Valdez, a Democratic Socialist state Assembly member, also won her primary against the preferred successor to retiring Rep. Nydia Velázquez.The results represent a significant political victory for the 34-year-old mayor and his growing movement, while raising questions about the direction of the Democratic Party heading into the 2026 midterms. Some party leaders have expressed concern that Mamdani and his allies could push Democrats further left on issues including immigration, affordability and the war in Gaza.The victories also marked a direct challenge to Washington Democrats, including House Democratic Leader Hakeem Jeffries, who campaigned against some of Mamdani’s endorsed candidates.Another Mamdani ally, Democratic Socialist State Assembly Member Claire Valdez, defeated the handpicked successor of retiring U.S. Rep. Nydia Velazquez (Getty)Before the results came in, Jeffries dismissed the idea that a handful of New York primaries could dramatically reshape the party.“We have agreed to strongly disagree,” Jeffries said. “There are 215 members of the House Democratic caucus. A handful of primaries that go in one direction or the other ... aren’t going to reshape who we are as House Democrats.”Mamdani celebrated the wins as evidence of a broader political shift.Democratic Congressional candidate Brad Lander greets his supporters after winning the 10th District Democratic primary (Getty)“A year ago, it was not the end of a political movement. It was the beginning,” he said at Valdez’s victory celebration in Brooklyn as supporters chanted “DSA.” Later, at Avila Chevalier’s Manhattan event, he said the results showed “a new path for politics in our city and in our country.”The candidates backed by Mamdani share several major policy positions, including calls to abolish Immigration and Customs Enforcement, increase taxes on wealthy Americans and take a more critical stance toward Israel’s military campaign in Gaza.Lander, in his victory speech, criticized President Donald Trump’s policies, called Israel’s actions in Gaza “genocide” and renewed his call to abolish ICE. He had also faced legal scrutiny earlier this month after being arrested during a protest at an immigration court building, though charges were later dismissed.The sweep also sends an undeniable message to establishment Democrats in Washington, including House Democratic Leader Hakeem Jeffries, who campaigned against Mamdani’s candidates and lost (AP)The Israel-Gaza war became a major dividing line in several races. Lander criticized Goldman for not using the term “genocide” to describe Israel’s actions, while Goldman has said he supports Israel’s security but has criticized Israeli government policies and settler violence.For some voters, the issue was decisive. Sara Hyler, 47, of East Harlem, said support for Espaillat from pro-Israel groups influenced her decision to back Avila Chevalier.“As much as I support Israel, I don’t think we should be paying for them,” she said.Meanwhile, Democrat Jack Schlossberg, the 33-year-old grandson of former President John F. Kennedy, failed in his bid to write his own chapter in Camelot lore as he competed in a crowded field for a seat being vacated by retiring U.S. Rep. Jerry Nadler (AP)Not every progressive candidate backed by the left prevailed. Jack Schlossberg, grandson of President John F. Kennedy, lost his bid for the seat being vacated by Rep. Jerry Nadler. State Assemblyman Micah Lasher, backed by party leaders, won the nomination in that race.On the Republican side, Trump-backed candidate Anthony Constantino won the GOP nomination for a House seat being vacated by Rep. Elise Stefanik. Constantino, a businessman and outspoken Trump supporter, is known for high-profile displays of loyalty to the former president, including a giant “Vote For Trump” sign and a pro-Trump music album.The New York primaries underscored a growing battle inside both parties — with voters rewarding candidates who embrace sharper ideological identities and rejecting some longtime political figures.