Zohran Mamdani just took his first steps toward remaking the national Democratic Party.

The New York City mayor took on his state’s Democratic establishment in three key congressional primaries Tuesday — and in all three, he prevailed.

Brad Lander, the former city comptroller who made an alliance with Mamdani when they were both running for mayor, took down two-term Rep. Dan Goldman in a landslide victory.

Claire Valdez, a Democratic Socialists of America member serving her first term in the state assembly, won an open House seat primary against the party leaders’ favored choice, Brooklyn Borough President Antonio Reynoso.

Most shocking of all was the victory of Darializa Avila Chevalier, a DSA member who argues that deportation is wrong and supports prison abolition, over a five-term member of Congress, Rep. Adriano Espaillat. If she now wins the general election, as expected, she’d likely be the furthest left member of Congress.

Mamdani had featured all three of the victorious candidates in his eye-catching “basketball ad,” aired during the New York Knicks championship playoff run — naming all three as part of his “team.” The results were a testament to his political strength and sway in the city — and showed again that the DSA can now take on and defeat the city’s traditional Democratic machines.

The results were also a dramatic demonstration of a new reality in Democratic primaries: that a record of strong support of Israel — which Goldman and Espaillat had — can be politically deadly.

All three of these districts are heavily Democratic, so Lander, Valdez, and Avila Chevalier are all nearly certain to win their general elections and head to Washington next year. If that happens, Mamdani will have helped coronate three new members of the House of Representatives, giving the mayor and his movement a growing beachhead in both New York politics and in Washington.

We are going to be hearing a lot about Darializa Avila Chevalier.

A DSA activist and organizer pursuing a doctorate in sociology, Avila Chevalier told my colleague Astead Herndon last week that she believes “all deportations are wrong.” And she is so opposed to incarceration that she’s hesitant to even say murderers should be locked up.

Yet she defeated a five-term member of Congress, beating Rep. Adriano Espaillat by a single-digit margin in this district that includes parts of Manhattan and the Bronx, including Harlem.

Espaillat, now 71 years old, had been an undocumented immigrant from the Dominican Republic as a child. After serving for 20 years in the state legislature, he was elected to Congress in 2016, triumphing in a bitter primary that divided Harlem’s Hispanic and Black establishments. He currently chairs the Congressional Hispanic Caucus.

But his record of support for Israel helped motivate Avila Chevalier’s challenge. She was a longtime supporter of Palestinian causes who helped organize protests of Israel’s war in Gaza on the Columbia University campus. She also attended a controversial pro-Palestinian rally in Times Square that was held the day after Hamas’s October 7, 2023, attacks.

Espaillat and his supporters tried to paint Avila Chevalier as an interloper — a “transplant” who isn’t truly looking out for longtime residents. But long-running establishment credentials don’t count for as much as they used to.

Lander stands apart from the trio of victorious Mamdani-endorsed candidates in a few ways.

He wasn’t backed by the DSA. And he’s not a political outsider coming from nowhere: He’s been a city council member and the city’s comptroller, and started off well-known and well-liked in this lower Manhattan and western Brooklyn district.

The incumbent, Rep. Goldman, has held the seat for two terms. Before that, he’d gained prominence as the lead counsel for House Democrats’ first impeachment of President Trump, back in 2019 and 2020. Then, in 2022, he prevailed in a crowded primary for this open House seat with a plurality of the vote.

But Goldman’s staunch support for Israel became a political liability when the war in Gaza horrified much of the Democratic base. Goldman also declined to endorse Mamdani during last year’s mayoral election.

Lander — who, like Goldman, is Jewish — chose a different path. He condemned Israel’s actions in Gaza as a “genocide.” And when Lander and Mamdani were both running for mayor, they “cross-endorsed” each other, campaigning hard against the initial frontrunner, Andrew Cuomo.

When he did not end up with a role in the Mamdani administration, Lander set his sights on challenging Goldman instead, believing him to be out of step with his base. That assessment proved correct — he defeated Goldman by about a 30-point margin.

Claire Valdez is a DSA activist and organizer who won a seat in the New York state assembly in 2024. She’s also a friend of Mamdani’s and was a very early backer of his mayoral campaign.

So when Rep. Nydia Velázquez (D) decided to retire after serving 34 years in Congress — and hoped to pick her successor — Mamdani turned down her suggested candidates, and backed Valdez for the Brooklyn and Queens seat instead.

Velázquez backed Brooklyn borough president Antonio Reynoso, who had sterling progressive credentials. His record of support for unions helped win him the backing of the New York Working Families Party (a progressive party that lends its endorsement to certain Democratic candidates) and the American Federation of Teachers.

But in the end, that didn’t mean much — Valdez defeated Reynoso by what was, as of Tuesday night, about a 20-point margin.

Israel was an issue in this race as well, though in somewhat more limited fashion: Both candidates criticized Israel for committing “genocide,” but Valdez argued that Reynoso did not do so early enough.

In the end, though, it was Mamdani’s endorsement that propelled Valdez — a previously little-known figure — past the choice of the district’s longtime Congress member and much of its progressive establishment.