Republican mayoral candidate Nicole Malliotakis suggested Friday that New York City could help the state-run subways by diverting rainy-day money the de Blasio administration has stocked away.

Malliotakis, who said she would accede to the Metropolitan Transportation Authority’s demand for half of an $800 million interim repair plan, criticized incumbent Bill de Blasio for failing to contribute enough to the ailing subway system.

“The money is there,” said Malliotakis, a state assemblywoman from Staten Island who voted for Trump, at a news conference outside the 59th Street-Columbus Circle subway station. “You have surpluses.”

Criticizing de Blasio for increasing spending every year since taking office in 2014, Malliotakis added: “We don’t need to cut anything.”

Nicole Gelinas, a senior fellow at the right-leaning Manhattan Institute, said the city has about $2 billion in reserves. De Blasio has said the city is bracing for a federal funding cut that President Donald Trump has threatened.

Malliotakis’ “idea is half-good, but she should put that money away and save it for later, when the MTA can demonstrate that it has a real plan for these upgrades,” Gelinas said.

In July, MTA head Joe Lhota unveiled a plan to address the ailing system, including at least 30 measures meant to fix the system, such as addressing fires, upgrading moribund signaling and hiring new workers.

Gelinas said New York City contributing to the plan would set a “bad precedent.”

De Blasio has refused to contribute, arguing that the city has already contributed $2.5 billion, that Gov. Andrew Cuomo effectively controls the agency, and that the state has siphoned nearly $500 million from MTA’s budget since at least 2011.

“Calling on the city to pay for this plan is signaling approval of the state stealing $456 million from the MTA over the last several years,” de Blasio spokesman Austin Finan said. “Anyone who believes New York City taxpayers should endlessly fund the state-run MTA, while the state steals money from that very system, has no regard for riders or our wallets.”

Jon Weinstein, Cuomo’s transportation spokesman, declined to comment.