Those moderates are cautioning that a party that increasingly seems confined to coastal big cities should not be so quick to adopt ideas and rhetoric that can easily be painted as extreme or foreign in much of the country.
As Mamdani aims to lead the nation’s most populous city - a place Democrats often turn to for both campaign cash and cultural cues - he has offered up his unabashedly left-leaning political brand as “a model” for the national party.
“A party where we fight for working people with no apology,” Mamdani said during his victory speech. “A life of dignity should not be reserved for a fortunate few. It should be one that city government guarantees for each and every New Yorker.”
Mamdani prevailed by focusing incessantly on the affordability challenges faced by New York residents, pledging to ease the cost of living by providing free childcare, freezing rent and making city buses free.
In a city home to the world’s largest population of billionaires, he pledged to fund his ideas by raising taxes on the wealthy.
Seeking to become the first Muslim mayor of a city with the world’s largest Jewish population outside of Israel, he did not shy away from criticising the Israeli Government for its handling of the war in Gaza.
In the wake of his better-than-expected showing, Republicans and pro-Israel groups have resurfaced clips of Mamdani embracing pro-Palestinian positions that his critics have branded as anti-Semitic.
Mamdani brushed aside those attacks during his campaign, pledging to be a mayor for all New Yorkers, but he is likely to face even more scrutiny of his foreign policy views ahead of the general election.
Already under pressure from Republicans to make their stance on Mamdani clear, some Democratic officials have begun publicly distancing themselves from him.
Representative Laura Gillen, a New York Democrat who defeated a Republican incumbent in November, sharply criticised Mamdani today, accusing him of “a deeply disturbing pattern of unacceptable anti-Semitic comments”.
“Socialist Zohran Mamdani is too extreme to lead New York City,” she said in a statement. “He is the absolute wrong choice for New York.”
Still, Mamdani’s campaign messages - and the buzzy, straight-to-camera way he often delivered them - will no doubt be studied by other Democrats seeking to capture some of the energy that propelled his upstart campaign from obscurity to victory.
While Mamdani’s opponents criticised him for his relative lack of experience and the implausibility of some of his policies, he framed his campaign as a fight on behalf of working New Yorkers too often left behind in a city known for displays of extravagant wealth.
As his campaign built momentum in the final weeks ahead of the primary, Mamdani racked up endorsements from other liberal politicians, including Representative Alexandria Ocasio-Cortez (Democrat-New York) and Senator Bernie Sanders (Independent-Vermont).
In what quickly became a kind of proxy for a broader struggle between the establishment and insurgent wings of the Democratic Party, Cuomo notched endorsements from former President Bill Clinton, Representative James Clyburn (Democrat-South Carolina) and former New York Mayor Mike Bloomberg.
As the vote totals came in showing Cuomo underperforming amid a clear surge in support for Mamdani across the city’s racially and generationally diverse five boroughs, party strategists were trying to determine how to interpret the results and prime Democrats for national success.
“Something that many of us who have been a part of the establishment know is that the establishment has been clinging suicidally to a version of power that no longer exists and that they no longer have,” said Amit Singh Bagga, a Democratic strategist.
“Instead of trying to eat the left for lunch, the establishment needs to understand how to work with the real people who have real problems.”
Others warned against reading too much into the New York results, given the city’s relatively low turnout, ranked-choice voting system, unique line-up of candidates and other peculiarities.
“There is more that Democrats can’t draw from it than what they can,” said Molly Murphy, a Democratic pollster who worked on the presidential campaign last year.
“City politics are always going to be different than federal or state, and Cuomo is a one-of-one figure with very specific and unique vulnerabilities that we should not project onto any other type of moderate or ‘establishment’ candidate.”
Still, Mamdani “did an excellent job of being authentic, sincere, and finding ways to find voters where they were,” Murphy said, adding that those lessons can apply to Democrats across the ideological spectrum.
Democrats will certainly be looking beyond New York for more evidence of what messages resonate with voters.
Races for governor in New Jersey and Virginia, for example, feature more mainstream Democratic candidates.
Former congresswoman Abigail Spanberger and Representative Mikie Sherrill, competing in their home states of Virginia and New Jersey, respectively, each have national security backgrounds and have eschewed the rhetoric of the party’s left wing.
Spanberger once lambasted left-leaning lawmakers after nearly losing her re-election in 2020, suggesting that talk of socialism and defunding the police had hampered the Democrats’ fortunes in the House.
Matt Bennett, co-founder of the moderate Democratic group Third Way, took to X today to brand politicians such as Spanberger and Sherill as “the party’s future”, advising Democrats in swing districts to distance themselves from socialism and Mamdani’s policies.
In his victory speech, Mamdani promised to be a leader who would listen to those who disagree with him and serve those who did not vote for him, “and to wrestle deeply with those disagreements”.
But even as he spoke, fierce debates were taking place among Democrats trying to extrapolate broader messages from the night’s stunning results.
“The establishment is cooked. Cuomo is a canary in the coal mine,” said David Hogg, the 25-year-old former vice-chairman of the Democratic National Committee who clashed with its leadership after pledging to target long-serving Democrats in safe congressional districts.
“If the party doesn’t fundamentally change, they will be voted out.”
For many Democrats, Cuomo’s defeat was yet another sign that Democrats need to chart a swift path away from older, establishment politicians who have struggled to resonate with modern-day voters.
The 67-year-old former governor was attempting a political comeback after resigning in disgrace amid sexual harassment claims.
The primary came almost one year after President Joe Biden’s disastrous debate performance against Trump sent the party into a spasm of handwringing over its decision to back an octogenarian president’s re-election during a time when voters seemed hungry for change.
Trump’s victory in November and his first five months in office have served to further destabilise the minority party.
While Mamdani’s performance appeared decisive in a city where Democrats far outnumber Republicans, his path to the mayorship is not a fait accompli.
Under the city’s ranked-choice voting system, a winner of the primary will probably not be certified before next week.
Incumbent Mayor Eric Adams, who won the Democratic primary four years ago, opted to run as an independent in November and has embraced a more moderate tone while cosying up to the Trump Administration.
Cuomo, who conceded defeat yesterday, has previously left open the prospect of running in the general election as an independent.
Republicans have already begun hammering Mamdani as an extremist whose policies will bankrupt the city and whose ideologies represent a kind of socialism that is foreign to the US.
The GOP successfully ran a similar strategy against Vice President Kamala Harris after Biden dropped out of the presidential race last year.
Representative Elise Stefanik (Republican-New York) began fundraising yesterday based on Mamdani’s performance.
“The idea that a self-avowed socialist and Hamas Terrorist sympathiser like Zohran Mamdani could become the next mayor of New York City truly makes me sick,” she said in a fundraising pitch sent by email.
While Mamdani has spoken out against anti-Semitism in New York, his past positions on Israel - including declining to condemn pro-Palestinian rhetoric such as “globalise the intifada”, which some Jews see as a rallying cry for violence against them - will no doubt become fodder for Republicans and raise uncomfortable questions for Democrats.
The war in Gaza, which has killed tens of thousands of Palestinians, has become a point of contention between liberal voters and Democratic stalwarts accustomed to voicing strong support for Israel.
For some in the party, Mamdani’s ability to stand up for his beliefs and run a successful campaign that connected with everyday voters was proof that Democrats can compete without retreating from bold positions.
“Look, we know the prospect of a Muslim democratic socialist becoming the next mayor of New York City is going to put the fear of God in establishment Democrats as well as Maga Republicans,” Singh Bagga said.
“What we have to remember is that the people of New York City tonight have spoken. They have spoken out against the lily-livered, lack-of-courage approach of Democrats in fighting authoritarianism.”