“Power concedes nothing without a demand,” Brooklyn state senator Jabari Brisport thundered on Sunday, quoting Frederick Douglass. “And our demand is — ?”

The crowd yelled back, “Tax! the! Rich!”

Twelve days after democratic socialist Zohran Mamdani’s historic election as New York City mayor, several hundred supporters gathered for a rally in Union Square kicking off New York City Democratic Socialists of America’s (NYC-DSA) “Tax the Rich” campaign, cosponsored by a coalition of unions and grassroots left organizations.

The rally addressed the need for revenue to fund public programs — especially those Mamdani ran on, like universal childcare, fast and free buses, and new public housing — but also the need for taxation to redress the outrageous inequality in New York City, in which children go hungry while, as another speaker put it, “some rich guy buys a third or fourth house.”

NYC-DSA, whose organizing played a key role in Mamdani’s victory, wasted no time in launching this campaign. “Tax the Rich” isn’t about the Left “holding Mamdani accountable,” a strategic position that would befit an organization that saw itself as outsiders to the Mamdani project. Rather, the immediate launch of the “Tax the Rich” campaign is indicative of a mature left claiming responsibility and ownership for Mamdani’s political victory — which, in turn, means working to create the conditions that can allow his mayoralty to succeed.

The campaign will try to mobilize the hundred thousand volunteers who knocked on doors to elect Mamdani to do similar work — canvassing, phone-banking, tabling — on behalf of his agenda. It will target Kathy Hochul, who is up for reelection next year, but also state senators and assemblymembers.

In 2021, NYC-DSA waged a similar campaign, winning an increased tax on millionaires, and billions of dollars for public schools, rent relief, relief for undocumented workers not covered by the federal COVID bill stimulus, and other public needs. The current campaign could draw momentum from the excitement of so many seeing Mamdani’s vision become a reality and can build on the field organizing structures and expertise that NYC-DSA has been developing for years. The NYC-DSA-endorsed politicians already holding state offices, like Brisport, will play a key role in lobbying and persuading their legislative colleagues.

For her part, Governor Hochul at first said she was opposed to taxing the rich but nonetheless wanted to work with Mamdani on universal childcare. She has now been heckled in public on the issue several times — at a preelection rally in Queens, for example, more than ten thousand people repeatedly chanted “Tax the Rich!” at her, and at the New York political gathering SOMOS in Puerto Rico, where, after a crowd again chanted the slogan at her, she insisted petulantly, “I’m the type of person — the more you push me, the more I’m not going to do what you want.” Despite this claim, Hochul has recently expressed an openness to new taxes, at least on corporations. That is a popular policy, as is taxing individual rich people, polling says.

This is the most important priority for the Left in New York to push right now. New York city and state have many unmet budget needs. Mayor-elect Mamdani has a mandate not only for his winsome smile but also for universal childcare, fast and free buses, and new affordable housing — all made possible by taxing the rich.

This is all doable, Nathan Gusdorf, executive director of the Fiscal Policy Institute, explained to me in an interview last Friday. Gusdorf says it’s not even completely crazy for Hochul to say that she could fund childcare without redistributive taxation: there is always a large state budget surplus, which explains how former mayor Bill de Blasio was able to fund universal pre-kindergarten despite then-governor Andrew Cuomo’s adamant opposition to taxing the rich.

But taxing the rich is the piece that makes the whole platform a realistic one and moves it out of a struggle for scant resources. Socialists don’t want to fund Mamdani’s platform at the expense of, say, smaller class sizes for third graders or adequate compensation for city workers. As Gusdorf points out, while the Left sometimes makes a big deal of allocations to state violence, policing is only about 6 percent of the budget, and “most of the stuff the government is doing is good.”

Mamdani’s plan to tax the rich is the main reason the city’s ruling class has found his rise so troubling. They’re terrified of the return of class struggle and of mass desire for the good life and abundant public goods.

Many have assumed that the federal situation bodes ill for New York, Mamdani, and his proposals. That’s not necessarily so, says Gusdorf, who says the state should be able to cover the health care cuts because of its practice of running high surpluses, and that the recently passed federal budget will have an otherwise “very minimal budgetary impact on New York City.” (Gusdorf laughs at my surprised reaction, acknowledging, “Normally, budget people don’t give you the good news.”)

What about Donald Trump’s threats to defund New York City, I ask? There, too, Gusdorf is actually optimistic: “I think it’s unlikely that we will see significant withholding of federal funds in New York City,” he says, saying that Trump’s threats are legally dubious.

Indeed, two days after we talked, on Sunday, Trump posted on social media that he’d heard from Mamdani and that the two would meet. The president insisted, “We’ll work something out. We want to see everything work out well for New York.”