Could 'Trump's worst nightmare' show how to take fight to president?

Zohran Mamdani calls himself "Donald Trump's worst nightmare".

They are the words of a man living the dream. It's because the 34-year-old is the headline act in Tuesday's referendum on Trump 2.0.

A statement night in US politics, as Americans - some, at least - deliver a verdict on what they've seen so far. Of four electoral contests across the US - including in California, New Jersey and Virginia - the race to be New York mayor is the most compulsive and consequential.

The polls have Mamdani, the Democratic nominee, as the frontrunner. If he wins, it would signify big change in the Big Apple.

Read more: Who is Zohran Mamdani? Born in Uganda to Indian parents (he moved to the US aged seven), Mamdani would become New York's first Muslim mayor. He is a democratic socialist whose supporters will see victory as laying down a template for taking on Trump, even if the party's old guard is sceptical.

An effective campaign has focused on the costs and quality of life in New York, promising universal childcare, a rent freeze, free bus travel and grocery shops run by the city. So why is he controversial? The message has resonated with New Yorkers squeezed on affordability, but his payment plan is open to question.

Mamdani plans to raise $9bn by raising taxes on the wealthy and on corporations, but he would face a struggle to gain the necessary consent of the New York State legislature and governor. Mamdani's politics are pegged to the "progressive" left wing of his party, and his campaign success plays into the Democrats' quandary around a longer-term comeback strategy.

The politics that succeed in New York don't necessarily resonate nationwide, and a party establishment has been reluctant to embrace Mamdani. Democrat Chuck Schumer, Senate minority leader, has declined to endorse him at all.

Party management aside, he won't have been impressed when Mamdani was arrested outside Schumer's Brooklyn home as part of a 2023 protest calling for a ceasefire following Hamas' October 7th attack on Israel. Mamdani has been a staunch critic of Israel and, in the past, has advocated defunding the police, decriminalising prostitution and closing New York City jails.

His background and Islamic faith are threaded through opposition attacks. He has been criticised for refusing to denounce the phrase "globalise the intifada.