The morning after Zohran Mamdani’s startling mayoral victory in New York, the most arresting visual image was not of the mayor-elect celebrating in an applause-filled room, but the breakdown of voting patterns across the city. Street by street, practically building by building, you could index New Yorkers’ support for Mamdani or Andrew Cuomo to the probable amount of rent they were paying. A middle-income precinct on the Upper West Side, for example, showed up as a small island of Mamdani voters in a sea of Cuomo-voting wealthier neighbourhoods. Solid lower-income support for Mamdani in modest midtown gave way to the incredible banking wealth of Tribeca and its majority support of Cuomo.

Allowing for large anomalies – Staten Island, a middle- to lower-income part of the city, voted heavily for Cuomo, as did lower-income Hassidic neighbourhoods in Brooklyn and Queens – the message of the huge turnout for Mamdani in the US’s most expensive city seemed to be one of affordability; even of a referendum on capitalism as we know it. And so the most pressing question became: was it a crank result from an unrepresentative city, or the beginning of a new political wave?

The night’s countrywide election patterns indicated a swing away from Donald Trump to the Democrats, which, of course, doesn’t mean that Mamdani’s Democratic socialism is anything the US at large will be willing to buy. Still, the move to the left was sharp enough to return Democrats to some traditionally very Republican areas, including two Democrats voted on to a public service commission in Georgia; the first Democratic female governor voted into office in New Jersey; and a new Democratic governor elected in Virginia. In New York City itself, the swing away from Trump, a mere 12 months after his support surged during the 2024 presidential election, was significant. In 2024, Trump won 94,000 more votes in the city than he had in 2016. But on Tuesday, his endorsement of Cuomo, running as an independent, made no apparent difference whatsoever.

It should be said that Cuomo was a terrible candidate, trailing sexual misconduct allegations – all of which he denies – and a record as New York’s governor that foundered horribly during the pandemic. It should also be pointed out that Mamdani didn’t simply beat Cuomo; he galvanised New Yorkers into the highest mayoral election turnout since the 1960s, indicating an electorate voting for him rather than against his opponent.

How, then, does the 34-year-old look as a potential leader beyond the very particular ecosystem of New York City, where, at times, it is possible to believe that a tub of margarine promising lower rents, higher minimum wage and fairer taxes might win out over a traditional political adversary? On this question, aspects of Mamdani’s identity – exploited by Cuomo and Trump to racist effect – might actually run in his favour. Mamdani’s age and eloquence obviously flatter him in relation to Trump, but it’s his background that stands out as a decisive advantage.

In his victory speech on Tuesday night, Mamdani promised working-class New Yorkers: “We will fight for you, because we are you.” This is a great piece of rhetoric, but let’s be honest: Mamdani has the social and cultural capital of someone who grew up in an affluent family in a wealthy part of Manhattan, with one parent who went to Harvard and became a successful film-maker and the other who is a professor at Columbia. And while the mayor-elect went to an academically selective state high school in the city, he attended a private liberal arts college in Maine that now charges $91,000 a year in tuition and living costs.

I don’t mention any of this to be snide. Mamdani sells a political message further to the left than any successful American politician has dared to in recent memory, but he doesn’t sound like an outsider. In fact, he sounds as smooth and polished and – can we say it – arrogant as any mainstream political contender.

He has neither Alexandria Ocasio-Cortez’s scrappy, up-from-her-bootstraps energy, nor can he be played for laughs on Saturday Night Live like Bernie Sanders – who, during the 2016 election cycle, Larry David mercilessly if affectionately skewered as a hopeless crank. Even Trump’s characterisation of Mamdani as a communist – the kind of absurd, inflationary claim the president is accustomed to throwing out and having his supporters swallow whole – withers under the slightest scrutiny.

Meanwhile, none of his campaign promises justify use of the word “radical” in the scaremongering sense. Mamdani’s push for a $30 minimum wage sounds like standard political aspiration. He has promised to make buses in New York free – as they were during Covid without the city falling to communism. (On which subject: when the Staten Island ferry went from fare-charging to free in 1997, New York’s commuters didn’t receive it as a communist gesture.) And his promise to increase taxes on those earning more than $1m a year is substantially more generous to affluent earners than anything Rachel Reeves – also not a communist! – is threatening in the forthcoming budget.

The election results this week suggest Mamdani as an effective, inspiring force against the corruptions of Trump. But while you can imagine him, years in the future, going toe to toe with JD Vance in a televised presidential debate, his real enemies may be closer to home. To advance beyond New York politics, it’s not just the Republicans he’ll have to beat, but the Chuck Schumer- and Nancy Pelosi-era gatekeepers of the Democratic old guard – who I suspect may find him even more threatening and obnoxious than Trump.