No wonder he doesn’t think there’s a problem.

The police have been laboring to keep Mayor de Blasio in a bum-free bubble — clearing nuisance-causing vagrants from his view at Gracie Mansion and as he travels in the city.

On Wednesday, two hours before de Blasio was due to walk through Washington Square Park, cops arrived en masse to clear out the quality-of-life-ruining bums who drink from paper bags, sprawl on benches and pee in public.

“They had to clear all the homeless out before he got there,” for a Ramadan fast-breaking dinner at the NYU Islamic Center, said one law-enforcement source.

“They didn’t want him to see the homeless people lying around, to see how the park usually is. They wanted it spotless for him,” the source added.

“The big push is on parks right now. To keep up appearances.”

One park-goer who witnessed the bum’s rush called the police deployment “ridiculous.”

“You looked around the park and said, ‘What is this s–t? Where the hell is everybody?’”

“[Homeless people] were everywhere, and they were clearing everyone out.”

Cops maintain a vagrant-free zone around Gracie Mansion and the surrounding Carl Schurz Park, a 15-acre quality-of-life oasis, according to the police, parks employees and dog walkers who frequent there.

“I’ve never seen anyone pissing here — you’d have to be crazy,” said Annette Lay, 29, as she walked her dog through the park on Friday.

“The main thing here is litter,” shrugged one parks employee who declined to give her name. “There’s not, you know, people passing out on benches in the daytime.”

A Post reporter who went undercover as a vagrant was promptly rousted from outside Gracie Mansion Wednesday.

“You see that big house up there? That’s the mayor’s house,” a cop told the reporter.

The mayor did come face-to-face with homeless people Thursday, when he visited Tompkins Square Park — after The Post wrote of the quality-of-life crisis there.

The Mayor’s Office and NYPD did not immediately comment.

Meanwhile, Washington Square Park was back to “normal” Friday.

“There’s masturbating, screaming at people, drugs — you name it,” said one cop. “This is every day, all day.”

Additional reporting by Tom Wilson and Georgett Roberts