New Yorkers were voting on Tuesday in a slate of Democratic primaries poised to reveal the strength of the party’s left flank and shape the battle for control of the US House of Representatives in November.

Voters in Maryland and Utah will also nominate congressional candidates on Tuesday, while South Carolina holds a series of runoff elections for candidates who did not receive a majority of the vote earlier this month.

But the New York contests, unfolding in a state expected to play a decisive role in determining the congressional majority, have attracted significant national attention as Democrats weigh competing visions for their party’s future in the Trump era.

With Republican holding a narrow House majority, Democrats hope to flip a crucial battleground district in the Hudson Valley, while defending three seats heavily targeted by the GOP.

In an ideological battle being closely watched by the party leadership, several self-identified democratic socialists are taking on more centrist Democrats in safe-blue seats, in an early test of mayor Zohran Mamdani’s political clout. Elsewhere, voters in New York’s wealthiest congressional district are weighing candidates in a race that has become a test of both the Kennedy name and the growing influence of the AI industry.

In New York City, the democratic socialist mayor, who was elected last year, has attempted to put a stamp on the state’s congressional delegation by backing a trio of leftwing congressional candidates, much to the chagrin of some in his party.

Two Mamdani-endorsed candidates – former New York City comptroller Brad Lander and public defense investigator Darializa Avila Chevalier – are running to unseat Democratic incumbents in safely Democratic districts, part of a coast-to-coast wave of ideological and generational challenges being waged against sitting members of Congress.

“People often ask me what I think of the state of the Democratic party. This slate here today is our answer,” Mamdani said at a rally with the candidates and Bernie Sanders on Thursday. “The Democratic party must change.”

He added: “The party of the past will not be what leads us into the future. We need a Democratic party with backbone.”

Lander ran for New York City mayor last year, eventually entering a “cross-endorsement” with Mamdani, as the pair sought to use the city’s ranked-choice voting system to ensure a progressive surpassed the former Democratic governor, Andrew Cuomo.

A survey in late May found Lander with a convincing lead over Dan Goldman in New York’s 10th congressional district, which includes lower Manhattan and a sizable chunk of Brooklyn, though polling in local elections can be volatile.

Goldman, who was first elected in 2022, has countered with support from House minority leader Hakeem Jeffries, as the Democratic party establishment has sought to push back against Mamdani and the party’s left wing.

Avila Chevalier, meanwhile, is challenging Representative Adriano Espaillat, a five-term Democrat and chair of the Congressional Hispanic Caucus. The 32-year-old democratic socialist has argued that the 71-year-old Espaillat is out of touch with the needs of the district’s young and working-class residents, while the congressman points to his experience and fierce advocacy, especially on behalf of immigrants and civil rights.

Claire Valdez, a democratic socialist also backed by Mamdani, is running for the open seat in New York’s seventh district, which encompasses parts of Brooklyn and Queens and is being vacated by Representative Nydia Velázquez after 17 terms in Congress. Valdez is facing Antonio Reynoso, the Brooklyn borough president, who has also won the endorsement of Jeffries as well as Velázquez and other establishment-aligned figures. The race has become a test of the new progressive wing of the Democratic party against its old guard.

Questions surrounding the candidates’ stances on Israel and the war in Gaza have also featured prominently in several of the city’s Democratic primaries. Lander and Valdez have both condemned Israel’s war on Gaza as genocide, as has a United Nations independent international commission of inquiry, while Goldman and Espaillat have faced attacks over their ties to the American Israel Public Affairs Committee, a pro-Israel lobby.

Meanwhile, the highly competitive primary in New York’s 12th district – the state’s wealthiest seat, and one which is safely Democratic – could see voters deliver a verdict on the limits of the Kennedy family influence.

Jack Schlossberg, the 33-year-old grandson of John F Kennedy, is arguably the most high profile of those running in the district, but his meme-heavy campaign appears to have fallen behind Micah Lasher, a New York state representative and self-described nerd, and Alex Bores, a state representative whose campaign has become a proxy war between AI companies.

AI investors have poured money into Super Pacs opposing Bores, furious over state legislation he proposed to regulate the industry. The primary contest also features George Conway, the Republican turned vocal Trump critic who has out-raised the field. Running on an aggressively anti-Trump platform, Conway has vowed to hold the president accountable if elected.

Beyond the city’s ideological battles, New York is set toplay a starring role in Democrats’ bid to wrest control of the House in November.

Republicans have a 217-212 majority, with five seats vacant and one occupied by an independent, but Trump is deeply unpopular nationwide and the midterm elections could be an opportunity for voters to rebuke the president over a less-successful-than-promised economy and his war in Iran.

Democrats hope a favorable political environment will help lift them to victory in New York’s 17th district, north of New York City, currently held by two-term Republican Mike Lawler. Former White House counter-terrorism official and army combat veteran Cait Conley and Beth Davidson, a local legislator, are among five Democrats vying to take on Lawler, who is viewed as one of Republicans’ most vulnerable incumbents in November.

The district was one of just three nationwide that voted, in 2024, for Kamala Harris for president but elected a Republican member of Congress.