NEW YORK (AP) — Former New York City Mayor Rudy Giuliani is breathing on his own after being hospitalized with pneumonia and placed on a ventilator, his spokesperson said Monday.

Giuliani, 81, remains in critical but stable condition at a Florida hospital and is being monitored as a precautionary measure, spokesperson Ted Goodman said.

Goodman said Giuliani’s condition was exacerbated by restrictive airway disease attributed to his exposure to dust and toxins from the Sept. 11, 2001, attack on the World Trade Center.

Giuliani’s hospitalization, near Palm Beach, Florida, came after he was heard coughing Friday on his nightly online talk show and hoarsely told viewers that his voice was “a little under the weather.”

“This condition adds complications to any respiratory illness, and the virus quickly overwhelmed his body, requiring mechanical ventilation to maintain adequate oxygen and stabilize his condition,” Goodman said in a statement.

Giuliani’s family and primary medical provider are by the former mayor’s side, Goodman added. He said they thanked well-wishers for an “outpouring of love and support.”

“The mayor believes in the power of prayer, and we are feeling that strength today,” Goodman said.

Giuliani’s eight-year tenure as the mayor of the nation’s largest city was punctuated by the 9/11 attack just months before he left office. He became celebrated as “America’s mayor” for his leadership, knighted by Queen Elizabeth II and named Time magazine’s Person of the Year.

Giuliani, a Republican, later made an unsuccessful run for president and was an adviser to President Donald Trump, spearheading his efforts to stay in office after his 2020 election loss.

Last year, Trump said he was awarding Giuliani the Presidential Medal of Freedom.

Giuliani coughed as he began his nightly online show “America’s Mayor Live” on Friday. As he spoke, he sounded more raspy than usual. Before launching into a commentary on the Iran war, he remarked: “My voice is a little under the weather, so I won’t be able to speak as loudly as I usually do, but I’ll get closer to the microphone.”

In a post on his Truth Social platform, Trump called Giuliani “a True Warrior, and the Best Mayor in the History of New York City, BY FAR.”

Giuliani was previously hospitalized last September after suffering a fractured vertebra and other injuries in a car crash in New Hampshire.

A native New Yorker, Giuliani was elected mayor in 1993 after serving as one of the nation’s highest-profile federal prosecutors, taking on mobsters and crooked Wall Street traders.

In 2016, Trump leaned on Giuliani’s political acumen and loyalty and put him to work as a surrogate leading attacks on Clinton, his Democratic rival. After Trump won, Giuliani continued as his attack dog, even traveling to Ukraine to seek damaging information about Biden’s son Hunter.