New York City Mayor Bill de Blasio took over the "best-run city" in the United States from his predecessor Michael Bloomberg, but it has been declining ever since, former Mayor Rudy Giuliani said Friday.

"It's going to get worse, and take a while because de Blasio was handed the best-run city in America by Bloomberg," Giuliani told Fox News' "Fox and Friends" about the mayor, who is seeking the 2020 Democratic presidential nomination. "If you are handed a great business, I don't care how dumb you are, how stupid you are, how lazy you are, it's going to work on its own for a while."

Giuliani said it "breaks my heart" to see the direction New York is headed under de Blasio, as he had worked "tirelessly" while in office from 1994-2001 to clean it up.

He added that he and Bloomberg don't see eye to eye on politics, but he still thought Bloomberg was a good mayor who kept the city running well. Now, Giuliani added, the homeless population is once again growing and the police department does not believe the mayor has its back.

"Look at the homelessness in the city," Giuliani said. "Homelessness was gone. There is a way to look at homelessness that these liberals just don't get. When I see a city with homeless people, I see a mayor who doesn't give a damn about people. When you give a damn about people, you don't let them sleep on the street."

Giuliani also said the city's police officers know de Blasio will not defend them "like I did," and that is hindering their decisions.