City Hall reached out to the MTA late Tuesday about the massive budget hole in its capital plan, which funds big projects like the Second Avenue Subway -- and said the deficit could bring the system to the decrepit conditions of the 1980s.

"The stakes are huge for everyone," wrote Deputy Mayor Anthony Shorris in a letter to the MTA chairman. "The system is already having difficulty accommodating record ridership -- now at over 8.6 million a day. Without a funding solution, the MTA will be unable to maintain the system in a state of good repair, forfeiting the progress that has been made in bringing the system back from the brink of collapse in the 1980s."

The MTA has been facing an almost $15 billion deficit in its capital plan, which keeps the transit system in good condition and pays for large projects like bringing the LIRR to Grand Central.

Shorris said the city is willing to work with the state to find a new source of money for the MTA, such as the MoveNY plan to change the tolls on its bridges and raising existing MTA taxes.

"We cannot saddle transit riders with the responsibility of ever higher mountains of debt, above and beyond the $35 billion the MTA already owes," Shorris said.

"And we surely cannot look to over-burdened riders to reach even deeper into their pockets than already planned in the MTA budget."

The head of the MTA said City Hall needs to be involved.

"The deputy mayor sent a letter saying he wants to sit at the table," said MTA chairman Thomas Prendergast. "He needs to have a seat at the table, and he will have a seat at the table."

MTA spokesman Adam Lisberg said the letter comes three months after the MTA sent asked for more capital funding from the city.

"The paltry amount the city has provided for decades -- especially given the city's recent historic surplus -- can't continue if we are to maintain a safe and reliable transit network, let alone improve and expand rider services," Lisberg said.

Mayor Bill de Blasio's spokeswoman Amy Spitalnick said it met the MTA's request for $657 million in capital funding in May, and that they then asked for more. She also said the city does not have a budget surplus.

Gov. Cuomo put pressure on the city to close the MTA's deficit, a state agency, Wednesday afternoon.

"The way you fill a gap is by providing resources to fill the gap," Cuomo told NY1. "And that's what the MTA has been asking the city. Can they help close the gap?"

Spitalnick fired back at Cuomo's remarks. "The governor is mistaken -- again," she said.

"The city increased our capital funding to fully meet the MTA's request, while also contributed $1 billion a year in operating funds. Meanwhile, the state continues to underfund the MTA despite having a surplus this year."