In a historic reshaping of New York’s political landscape, Mayor Zohran Mamdani and the democratic socialist movement achieved a stunning clean sweep in Tuesday’s high-stakes congressional primaries, successfully unseating two entrenched Democratic incumbents and securing an open progressive stronghold. By leveraging a highly disciplined ground operation to dismantle corporate-backed party machine infrastructure, Mamdani’s insurgent slate has not only altered the balance of power within the state’s federal delegation but has also established a powerful new blueprint for progressive primary challenges nationwide.
NEW YORK CITY – June 25, 2026 (STL.News) Six months ago, critics and moderate commentators characterized the ascension of Mayor Zohran Mamdani to City Hall as an anomalous byproduct of ranked-choice engineering—a fragile progressive coalition bound to fracture under the pragmatic pressures of municipal governance. On Tuesday night, Mamdani did not merely answer his skeptics; he systematically dismantled the institutional architecture of New York’s Democratic establishment.
In a stunning display of calculated political leverage, Mamdani and his allies within the Democratic Socialists of America (DSA) executed an unprecedented clean sweep across three highly contested congressional primaries. By leveraging his fresh mayoral capital, a highly organized ground game, and deep programmatic discipline, Mamdani engineered the ouster of two sitting members of Congress and secured the succession of a third deep-blue stronghold.
The result is a seismic reordering of power that reverberates far beyond the borders of the five boroughs. In a single evening, Mamdani transitioned from an insurgent municipal chief executive to an undisputed national kingmaker, proving that the progressive movement can decouple itself from party machine infrastructure and win decisively on its own terms.
The Upset of the Decade: NY-13 and the Fall of the Machine
The epicenter of the political earthquake was New York’s 13th Congressional District, which stretches across Upper Manhattan and parts of the Bronx. Here, public defense investigator, doctoral student, and former Mamdani campaign organizer Darializa Avila Chevalier did what many political operatives deemed impossible: she unseated five-term incumbent Representative Adriano Espaillat.
Espaillat, 71, was no ordinary backbencher. As the influential chairman of the Congressional Hispanic Caucus and a towering figure in Dominican-American politics, he had a multi-decade career, from state offices to Capitol Hill, backed by an entrenched regional machine. During the campaign, independent expenditures and super PACs poured more than $7 million into the district to shield Espaillat, attempting to characterize the 32-year-old Avila Chevalier as a detached transplant.
Instead, Avila Chevalier transformed the incumbent’s financial advantages into an indictment of corporate-backed machine politics. Focusing heavily on campaign finance reform, she critiqued Espaillat’s substantial funding from real estate lobbies, immigration enforcement contractors, and the American Israel Public Affairs Committee (AIPAC).
When the unofficial election night returns were compiled, the depth of the upset became clear:
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The Margin: Avila Chevalier secured 49% of the vote to Espaillat’s 45%.
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The Geographic Split: While Espaillat held his ground in the Bronx portion of the district (winning 4,987 votes to Avila Chevalier’s 2,709), the challenger completely overwhelmed the incumbent’s machine in Manhattan, capturing 30,061 votes to Espaillat’s 25,445.
With her victory, Avila Chevalier becomes the first woman ever elected to represent the historic 13th District, signaling a profound generational and ideological realignment within the city’s working-class Latino electorate.
Redefining the Intellectual Left: Lander Ousts Goldman in NY-10
Simultaneously, in New York’s 10th Congressional District—comprising Lower Manhattan and brownstone Brooklyn—former City Comptroller Brad Lander secured a dominant victory over two-term centrist incumbent Representative Dan Goldman.
The race was highly unique, presenting an ideological battleground over the future direction of progressive Jewish politics in America. Goldman, a lead house counsel during Donald Trump’s first impeachment trial, campaigned as a reliable institutionalist aligned with the party center. Lander, conversely, occupied the further-left flank.
Though Lander lacked a formal DSA endorsement, his structural ties to the mayor were explicit. During the previous year’s mayoral primary, Lander and Mamdani had engaged in a strategic cross-endorsement alliance that ultimately propelled Mamdani to victory. On Tuesday, that alliance bore national fruit.
The primary acted as a referendum on U.S. foreign policy toward Israel and Gaza. Lander, a self-described “liberal Zionist” backed by progressive Jewish groups like Jews for Economic and Racial Justice (JFREJ), directly accused the Israeli government of apartheid and genocide. Goldman, while critical of Prime Minister Benjamin Netanyahu, maintained a stance closely aligned with mainstream Democratic leadership.
The contest was expected to be tight, but the Mamdani-backed ground operation triggered an early landslide:
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With 80% of the vote counted on Tuesday night, the Associated Press swiftly called the race for Lander, who commanded 66% of the vote over Goldman’s 33%.
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By the time counting reached 92%, Lander maintained an unassailable 31-point lead.
In his victory speech, introduced by Mamdani himself, Lander explicitly framed the outcome as a structural shift:
“This race was about more than a single seat in Congress. It was a fight for both the future of the Democratic Party, and the future of the Jewish community.”
Securing the Legacy: Valdez Takes NY-7
The third prong of the Mamdani slate focused on consolidation in New York’s 7th Congressional District, a historic progressive enclave cutting across Brooklyn and Queens, often referred to by activists as the city’s ideological engine room.
Following the retirement announcement by 17-term veteran Representative Nydia Velázquez, a proxy war emerged over the seat’s future representation. Velázquez attempted to hand-pick her successor, throwing her formidable endorsement behind Brooklyn Borough President Antonio Reynoso, an established progressive figure within traditional city politics.
However, the modern progressive vanguard chose a different path. State Assembly member and DSA stalwart Claire Valdez, explicitly endorsed by Mayor Mamdani, ran an insurgent campaign that argued the district required a structural socialist voice rather than an establishment progressive. Valdez successfully leveraged the mayor’s deep popularity in Queens and Brooklyn to out-mobilize Reynoso, winning the primary and securing a clear path to Washington in this heavily Democratic district.
The Establishment Retains a Foothold: NY-12
The progressive wave, however, did find its absolute limit in Manhattan’s 12th Congressional District. In the race to succeed retiring 17-term Representative Jerry Nadler, the traditional Democratic establishment demonstrated that its defensive perimeters could still hold when unified.
State Assembly member Micah Lasher—who commanded the combined backing of Nadler, Governor Kathy Hochul, and former Mayor Michael Bloomberg—successfully defeated a crowded, high-profile field. Lasher’s opponents included state Assembly member Alex Bores, prominent anti-Trump conservative legal figure George Conway, and Jack Schlossberg, the grandson of President John F. Kennedy. Lasher’s victory provided a solitary point of comfort for moderate Democrats seeking to preserve an establishment presence in Manhattan’s federal delegation.
