Zohran Mamdani — the 33-year-old former amateur rapper, Democratic Socialist, and likely next mayor of New York City — has a lot of ideas. But the most impactful thing Mamdani might do as mayor isn’t freezing the rent or making buses free (it’s not clear the mayor can even do that stuff). Rather, Mamdani could enter Gracie Mansion and enact a long-held socialist dream: shuttering New York City’s jail system.

Under current law, New York will close the infamous Rikers Island jail complex in August of 2027. The facilities meant to replace it, everyone agrees, are unlikely to be ready by then. Yet somehow, no one seems interested in addressing the impending crisis — especially not Mamdani, a committed prison abolitionist. In fact, to free 7,669 people currently held before trial — mostly charged with crimes like murder, robbery, and rape — all Mamdani will have to do is… nothing.

How is this possible? Roll the clock back to 2019, when the New York City Council passed a law requiring that Rikers close. In its place, the plan is to build four jails in the city proper, one in each borough except Staten Island. That plan reflected the idea that Rikers was dangerous, dysfunctional, and cruel (fair, given that it’s now in federal receivership). It was also a triumph for the then-ascendant criminal justice reform movement.

But while Rikers has problems, the idea of building four massive jails on some of the most expensive real estate in the world in just eight years was always implausible. It only became more unrealistic as the Covid pandemic and Biden inflation drove up labor costs and wait times. Earlier this year, the city commission that first called for closing Rikers admitted there’s no way the city will hit its 2027 deadline. The Brooklyn jail is now expected to open in 2029, the Bronx jail in 2031, and Queens and Manhattan’s facilities in 2032.

In other words, New York City legally must close Rikers in August 2027 with no suitable replacements. Mayor Eric Adams has agitated for extending the timeline, but found himself at an impasse with the City Council; he’s now floating repairing, instead of closing, Rikers.

Into this mess, add Zohran Mamdani.

Mamdani, among his other radical bona fides, is a committed prison abolitionist. He’s repeatedly called to “abolish” incarceration, writing on X that “the entire carceral system is an unreformable public health hazard.” Asked whether prisons are “obsolete,” Mamdani replied in an unearthed clip, “what purpose do they serve?” He’s also called violence “an artificial construction.”

Mamdani has walked back some of his prior radicalism on the campaign trail. But he told The City that he supports closing Rikers, and would work with DAs to “release more people pretrial or divert them from prosecution entirely.” That’s typical of a committed criminal justice system reformer who, for example, once voted against punishing people who assault transit workers.

Years of reform mean that almost everyone who can be diverted from Rikers already is. As of this writing, there are only about 6,300 people detained pre-trial in NYC jails on Rikers (another 1,400 or so are being held there serving short post-conviction sentences, or they’re parole violators, or in transit to go upstate). 1,550 of them are in on murder or attempted murder; another 3,200 are in on robbery, assault, burglary, firearm or sex offenses. Under the state’s infamously lenient bail laws, 100 percent of Rikers detainees have been ruled a flight risk. Does Mamdani plan to put these people back on the street?

Some may expect a future Mayor Mamdani to accelerate construction of the four replacement jails, but that’s unlikely. The city’s recently passed budget deprives it of funds it could use to hasten the process. And even if it had the money, New York is three years past deadline and $100 million over budget on another 104-bed jail inside of Bellevue Hospital. If New York can’t even open a 104-bed facility, what hope is there it can expedite four new buildings with 30 times the capacity?

Where will all these criminals go, if not Rikers? Legally, New York City can ship its detainees to other counties’ jails. About 1 percent of prisoners statewide were originally held in NYC before being transferred. In theory, Mamdani could try to shift thousands of detainees to Westchester or Long Island — but doing so would be hugely expensive (because the city would have to pay other counties for their beds) and unprecedented in its scale.

It’s easier to imagine Mamdani standing on principle, and attempting to divert everyone flowing into Rikers, instead releasing them on their own recognizance or with minimal check-ins and other monitoring. Doubtless, the resultant crime spike will make him and the Council change course. But we’ve been given no reason to believe the crisis will be averted before it happens.

No matter who wins the mayoral race, the Rikers time bomb will keep ticking. New Yorkers need to ask mayoral candidates how they plan to defuse it. By all accounts, the leading candidate seems ready to let it explode.

—Charles Fain Lehman

Charles Fain Lehman is a fellow at the Manhattan Institute and senior editor of City Journal.