If Donald Trump becomes president, the Secret Service would “strongly recommend’’ that he not stay at his Trump Tower penthouse when he’s in the city, law enforcement sources told The Post.

The Fifth Avenue skyscraper is a public building where residents and their guests can come and go — a security nightmare, sources said.

“It’s definitely a strong concern that he doesn’t stay there, because it would be a lot harder to protect him there, a lot harder to secure,’’ a source said. “It’s not like Camp David, where no one can get to it.’’

Trump, his wife, Melania, and their son, Barron, live in a 66th-floor, gilded triplex palace with sweeping Central Park views. It’s reportedly worth $100 million.

After Trump secured the GOP nomination in July, Trump Tower began undertaking its own extra security measures, including checking IDs of anyone entering the building and requiring tenants to fill out applications for all visitors.

But law enforcement say it won’t be enough if Trump wins the White House.

“He’s not liked,” one source said bluntly. “So there’s the concern of someone taking a shot at him.”

Another source added that agents believe that Trump would not listen to their concerns if he wins.

“They can tell him, but he’ll do whatever he wants. At the end of the day, he’ll probably do what he wants to do,” a source said.