Rudy Giuliani, a former New York City mayor, is breathing on his own after being hospitalized with pneumonia and placed on a ventilator, his spokesperson said on Monday.

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

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

Giuliani’s hospitalization, near Palm Beach, Florida, came after he was heard coughing on Friday on his nightly online talkshow and hoarsely told viewers 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.

He described Giuliani as “the ultimate fighter” and said, “he is winning this battle”.

Giuliani’s family and primary medical provider were 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. He was an adviser to Donald Trump and spearheaded his efforts to stay in the Oval Office after he lost the 2020 presidential election to Joe Biden.

In that role, Giuliani became a vocal proponent of the president’s allegations of fraud in his defeat by Biden. Trump and his backers lost dozens of lawsuits claiming fraud, and numerous recounts, reviews and audits of the election results turned up no signs of significant wrongdoing or error.

Two former Georgia election workers later won a $148m defamation judgment against Giuliani. As they sought to collect the judgment, the former federal prosecutor was found in contempt of court and faced a trial over the ownership of some of his assets.

Giuliani ultimately struck a deal that let him keep his homes and various belongings, including prized World Series rings, in exchange for unspecified compensation and a promise to stop speaking ill of the ex-election workers.

In September, Giuliani was hospitalized after suffering a fractured vertebra and other injuries in a car crash in New Hampshire. Trump that same month said he was awarding Giuliani the Presidential Medal of Freedom, the US’s highest civilian honor.

Giuliani coughed as he began his nightly online show America’s Mayor Live! on Friday. He sounded more raspy than usual as he spoke. 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”, among other things.