New York City mayoral candidate Zohran Mamdani speaks during a 'New York is Not For Sale' rally at Forest Hills Stadium in the Queens borough of New York City.

• Prominent leftists boosted New York mayoral hopeful Zohran Mamdani.
• Senator Bernie Sanders and Representative Alexandria Ocasio-Cortez spoke on Mamdani’s platform.
• Mamdani leads Andrew Cuomo and Curtis Sliwa, according to polling.

New York mayoral hopeful Zohran Mamdani was boosted by prominent US leftists at a get-out-the-vote rally on Sunday, as the Democratic socialist and Donald Trump foe closed in on the city’s top job.

Senator Bernie Sanders and Representative Alexandria Ocasio-Cortez spoke ahead of Mamdani, who has gone from an outsider to the unpredictable race’s frontrunner - and a standard bearer with them on the Democratic Party’s left.

Sunday’s rally at a Queens stadium came after early voting in the city of 8.5 million began the day before, with Election Day scheduled for 4 November and the new mayor taking office in the new year.

Ocasio-Cortez, whose congressional district contains portions of Queens, said that on election day “we will send a loud message to President Donald Trump that his authoritarianism is no good here,” sparking chants of “AOC”.

Sanders, of Vermont, said “people all over the world are paying attention to what will happen here on Tuesday.”

READ | New York AG defies Trump: ‘I fear no man’, throws weight behind Zohran Mamdani for mayor

“These are not normal times... this election takes place at a time when we have a president who has given a trillion dollars in tax breaks to the top one percent,” he said.

“She’s there for working people,” Mamdani said of AOC, after struggling with a defective teleprompter.

“The senator (Sanders) dared to stand alone for so long. I speak the language of Democratic socialism only because he spoke it first.”

The latest citywide poll by Victory Insights showed Mamdani at 47% support, followed by former governor Andrew Cuomo - who lost the Democratic primary but is running as an independent - at 29%.

Republican Curtis Sliwa trails at 16%.

Starbucks worker Kai Fritz told AFP he was attending the rally “because I know New York is not for sale”.

“This is a broken system, but we are fighting back.”

A crowd of thousands pounded their feet on bleachers creating a thunderous sound as the sun set over the wealthy Forest Hills neighbourhood.

As the light dimmed and the night chilled, the smiling crowds held up cell phone lights giving the gathering a festival-like atmosphere.

Comedians, poets, and activists spoke ahead of 34-year-old Mamdani, Sanders and Ocasio-Cortez, framed by banners reading “universal childcare”, “freeze the rent” and “making buses fast and free”.

In the race’s latest twist, scandal-tainted current mayor Eric Adams gave public backing to 67-year-old Cuomo - after previously calling him a “snake and a liar”.

On Sunday the crowd noisily booed when Trump, who has called Mamdani “a little communist”, was mentioned.

“We are a working people’s borough in a working people’s city,” Ocasio-Cortez said to huge cheers.

“And all of that makes us a fascist’s worst nightmare,” she said.

New York city comptroller and Mamdani ally Brad Lander said “it’s not Donald Trump versus Zohran Mamdani, it’s Donald Trump versus New Yorkers.”

The race has been dominated by the issue of cost of living, as well as by how each candidate would handle Trump, who has threatened to withhold federal funds if Mamdani is elected.