As the Left’s Biggest Stars Unite Behind Mamdani, a Bigger Test Awaits

For the Democratic Party’s left flank, the stage is set: Zohran Mamdani, Senator Bernie Sanders and Representative Alexandria Ocasio-Cortez are to unite on Sunday for a massive rally to celebrate Mr. Mamdani’s front-running campaign for mayor of New York City.

But even if Mr. Mamdani wins the Nov. 4 election, he and his movement may face a far tougher challenge than even a long-shot campaign: running the largest city in America and proving to the political world that their liberal agenda can be replicated across the country.

Mr. Sanders, Ms. Ocasio-Cortez and their democratic socialist allies in elected office have crafted legislation, pushed Democratic policy to the left and periodically driven the national political conversation. But their movement has never captured an executive position with as much power as the mayor of New York City.

“The stakes are high for the movement and for democratic socialists in general,” said Julia Salazar, a democratic socialist state senator in New York. “It’s certainly consequential politically but also consequential in a material way for millions of people.”

A decade ago, Mr. Sanders’s come-from-behind presidential primary bid pushed democratic socialists from the fringes into the political mainstream. In 2018, Ms. Ocasio-Cortez’s surprise victory and social media savvy expanded their power, growing their clout on Capitol Hill and in state governments across the country.

Now, should he win, Mr. Mamdani will face the biggest opportunity to put their policies into practice.

But his opponents, including some Democrats, believe that Mr. Mamdani can just as easily become an example of the failures of democratic socialism.

“There are two tests: the basics of running the city day to day and then the socialist-plus promises that he’s made a lot of which are not only unattainable and impossible but insane,” said Representative Josh Gottheimer, a moderate Democrat who represents the city’s New Jersey suburbs and opposes Mr. Mamdani’s bid.

In other cities, democratic socialists have found their goals stymied by the same forces that impede many politicians, such as a finite budget, difficulty building alliances and government dysfunction.

If elected, Mr. Mamdani will assume the mayoralty having set an extraordinarily high standard for his own success. His meteoric rise through the race has been fueled by a promise to make the city more affordable through four signature policy proposals. He has promised universal child care, free buses, city-owned grocery stores and a rent freeze on rent-stabilized apartments.

But voters are likely to assess his performance on rather prosaic concerns, including trash, crime, schools and, of course, rats.

“We all understand that the stakes are high and any lack of ability to deliver gets amplified 8,000 times,” said Representative Pramila Jayapal, a progressive Democrat from Washington State. “Picking up the trash is probably as important as delivering child care or free buses.”

Since winning the nomination, Mr. Mamdani has made a conspicuous effort to expand his appeal. He has shed some liberal positions he held in the past, promised to apologize for comments calling the Police Department racist and announced that he intended to ask Jessica Tisch, the billionaire heiress appointed by Mayor Eric Adams who has pushed for stricter criminal justice laws, to stay on as police commissioner.

He has also distanced himself from specific policy goals of the democratic socialist movement, differentiating his platform from the group’s national agenda.

“I am both a democratic socialist and I’m also a Democrat,” he told The New York Times. “One is a description of my political ideology, the other is a description of the party that I belong to.”

But even as he stands on the precipice of running the nation’s financial center, he is not shrinking from his roots in democratic socialist and left-wing organizing — a point made obvious by his late-stage appearance with the biggest stars of the progressive left, both of whom are also democratic socialists.

Their support is a homecoming of sorts for Mr. Mamdani, who has described Mr. Sanders as “the single most influential political figure in my life.” His 2016 presidential run inspired Mr. Mamdani to formally join the Democratic Socialists of America.

Representative Greg Casar, a Texas Democrat and chairman of the House Progressive Caucus, noted that some of the proposals being pushed by Mr. Mamdani had been implemented in other cities, including in his own district, which includes Austin and San Antonio.

But those plans have not received the same level of scrutiny as Mr. Mamdani is likely to face.

“New York City is New York City,” said Mr. Casar, who has spoken with Mr. Mamdani about his campaign and policy agenda. “Through his campaign and what he can achieve as mayor, Zohran can show how big ideas aren’t just for progressives but the overwhelmingly amount of people.”

Even in New York, Mr. Mamdani’s plans will face serious obstacles. His four core policy proposals could cost nearly $7 billion every year, exceeding the Police Department’s budget and representing a 6 percent increase in the city’s nearly $116 billion budget. He has proposed paying for his plans by raising income taxes on wealthy residents and corporate taxes on businesses, moves Gov. Kathy Hochul opposes. She did, however, express openness to his plans for universal child care when she endorsed his candidacy last month.

Other powerful figures in New York politics have been slow to embrace Mr. Mamdani’s bid. Senator Chuck Schumer, the minority leader, and Senator Kirsten Gillibrand — powerful allies in Washington whose backing could very well be crucial to his success as mayor — have refused to support him.

Representative Hakeem Jeffries, the House Democratic leader, waited until a day before early voting began to endorse his campaign, saying in a statement that he expected “areas of principled disagreement” with Mr. Mamdani, should he win.

For his part, Mr. Mamdani has tried to signal that he recognizes the importance of making good on his big promises, even if it involves expanding his ideological tent.

“The most important thing is delivering,” he said in an interview on the New Yorker podcast. “If that is your framework, then you have to be willing to listen to everyone who can bring you closer to that.”

He has met with skeptical rabbis and business leaders, as part of a charm offensive to build relationships with those who have opposed his bid. And he has said he would be open to other sources of revenue for his plans, rather than raising taxes on wealthy New Yorkers and corporations.

But he has never wavered from his embrace of the political message of Mr. Sanders, the most prominent democratic socialist in the country.

When the two campaigned together at a Brooklyn town hall event last month, Mr. Mamdani cast himself in Mr. Sanders’s image, saying the senator’s first presidential campaign gave Mr. Mamdani “the language” to describe his own beliefs.

As the crowd of students, activists and voters cheered, Mr. Mamdani promised that their movement was just beginning.

“We are not just here together with the message to come out and vote in November,” he said. “We have an agenda to win. The promises we have made are promises we must keep.”