The Secret Service is in negotiations with the Trump Organization to take over two vacant floors in the gilded 68-story Fifth Avenue tower, law enforcement sources told The Post.

The federal agency and the NYPD plan to run a 24/7 command post out of the space that would be housed at least 40 floors below Trump’s $90 million penthouse triplex, where wife Melania and their 10-year-old son Barron will continue to reside at least through the spring, sources said.

The first 26 floors of the glass-clad skyscraper are commercial tenants while the remaining levels are luxury apartments.

But several commercial floors are currently vacant, sources said. The Secret Service is eyeing two contiguous floors for over 250 agents and cops, sources said.

The Secret Service must protect the president and his family wherever they go, including visits back to their permanent homes.

For example, the Secret Service paid Vice President Joe Biden $2,200-a-month, to rent out a cottage next to his Wilmington, Del. home, according to a 2011 article in The Washington Times.

And when President Barack Obama spent summer vacations on Martha’s Vineyard and his annual Christmas vacation to Hawaii, his security detail rented private homes and hotel rooms and set up land and sea perimeters over the short stay.

The same is expected when Trump visits his Mar-a-Lago estate in Florida as he and his family are doing for the Thanksgiving weekend. Similarly, it cost roughly $2 million a year for the U.S. Coast Guard to station boats off the coast of George H. W. Bush’s Kennebunkport, Maine estate during his presidency.

But in the case of Trump Tower, taxpayers would be paying the president-elect’s own corporation to lease the two floors, aside from the cost of agents, staff and equipment and barriers that are normal in such cases.

The lease deal alone could cost more than $3 million a year, based on prevailing rates in the building.

The Post reported earlier this week that the 17th floor at Trump Tower is available. The floor is currently being marketed in three, 3,000- to 5,000-square-foot parcels at up to $105 per square foot.

At that rate the federal government would be paying $1.5 million a year for just one floor and double that for two levels of Trump Tower offices.

The ready-to-rent 17th floor includes six large south-facing outdoor terraces, private elevators, polished concrete floors — but no brass.

The 15th floor may also be available. The Trump Campaign operated mainly out of that level plus other areas, paying $169,000-a-month for rent and utilities, according to the Federal Election Commission.

Reps for the Trump Organization and the Secret Service did not return messages seeking comment.

The government tenant would be a boon for the building that’s seen a nearly 40 percent rate slash for sales and rentals of residential units in the past year, according to a recent article in The Hollywood Reporter.

Approximately 15 percent of the residential space is for rent or sale while the rest of the luxury housing market enjoys low vacancy rates, the entertainment web site said.

A top Manhattan real estate broker said an exodus is underway at the once sought-after building.

“These are wealthy people. They don’t need this, and they can’t take it any longer. They no longer want to stay there,” the broker told The Post in early November.

The marble-lobbied building is home to art dealer Helly Nahmad and Trump’s former campaign manager Paul Manafort. Past residents include Michael Jackson, Liberace and Andrew Lloyd Webber.