Zohran Mamdani built the greatest field operation by any political campaign in New York's history-by getting citizens to talk to each other.Can Democrats learn from his success? 'Unstoppable force' that drove victory

A WEEK BEFORE ZOHRAN MAMDANI'S convention-shattering victory in the New York City mayoral election, members of his vast army of youthful volunteers were amply aware of what was at stake.

- Ed Pilkington NEW YORK CITY

A group of 16 had assembled in the bohemian Hispanic neighbourhood of Bushwick in Brooklyn for one last push to heave the Democratic candidate over the line. Juuli, the field lead of the group who was coordinating that night's canvassing on behalf of the Mamdani campaign, was running through the key messages for voters on the doorstep. Emphasise the candidate's policy platform promising to make New York a more affordable city, she said.

And there was one other thing she wanted the volunteers to stress, which they wouldn't find in the official campaign script. "Remember to mention that he's the Democratic nominee for mayor of New York City, not just some social media guy." Last week, that social media guy pulled off one of the great upsets in American politics in the era of Donald Trump. He defeated the Democratic behemoth and former New York governor Andrew Cuomo, who was running as an independent, and the Republican Curtis Sliwa to become leader of the country's largest city and its first Muslim mayor.

An unashamed democratic socialist had won control of the capital of capitalism.

He did so having catalysed the larg est voter turnout in the city in more than half a century. And that in turn was in no small part achieved through his foot soldiers, who gathered nightly in Bushwick and in every pocket of New York to spread the word.

By election night, that volunteer army had grown to more than 100,000, making it the greatest field operation by any political campaign in New York's history. Mamdani paid homage to it in his victory speech, lauding it as an "unstoppable force" that with every door knocked on and every hard-earned conversation had "eroded the cynicism that has come to define our politics".

This is the stuff of political legend.