Rudy Giuliani was hospitalized with pneumonia and remains in critical but stable condition, his spokesperson, Ted Goodman, said Monday.

“Mayor Rudy Giuliani is recovering from pneumonia and is being monitored as a precautionary measure," Goodman said in a statement, adding that Giuliani, the former mayor of New York, had been diagnosed with restrictive airway disease in the wake of the Sept. 11 attacks.

That condition adds "complications to any respiratory illness" and caused Giuliani to be quickly overwhelmed by the viral lung infection, requiring "mechanical ventilation to maintain adequate oxygen and stabilize his condition," Goodman said.

"He is now breathing on his own, with his family and primary medical provider at his side," Goodman added.

Goodman said Sunday that Giuliani, 81, the longtime friend and ex-lawyer for President Donald Trump, was in the hospital but didn't provide details about what was ailing him.

"Mayor Giuliani is a fighter who has faced every challenge in his life with unwavering strength, and he’s fighting with that same level of strength as we speak,” Goodman said Sunday on X.

“We do ask that you join us in prayer for America’s Mayor Rudy Giuliani,” Goodman added.

He did not specify which hospital admitted him.

Trump confirmed Sunday that Giuliani was hospitalized in a post that took political shots at Democrats.

"Our fabulous Rudy Giuliani, a True Warrior, and the Best Mayor in the History of New York City, BY FAR, has been hospitalized, and is in critical condition," Trump wrote on Truth Social.

"What a tragedy that he was treated so badly by the Radical Left Lunatics, Democrats ALL — AND HE WAS RIGHT ABOUT EVERYTHING!" Trump added. "They cheated on the Elections, fabricated hundreds of stories, did anything possible to destroy our Nation, and now, look at Rudy. So sad!"

Giuliani hosted his show "America's Mayor Live" on Friday night from Palm Beach, Florida. As he kicked off the show, he noted his voice was "a little bit under the weather" after he coughed.

Giuliani, who was Trump's personal lawyer, represented Trump in lawsuits trying to overturn the 2020 election results. He was disbarred in New York and Washington, D.C., over his involvement in those efforts.

In November, Trump pardoned Giuliani and dozens of other people accused of having some involvement in trying to overturn the 2020 election. The pardon was largely symbolic, as none of the people who were pardoned had been convicted of federal crimes.

He also faced state charges in Georgia and Arizona for his actions following the 2020 election and was named as an unindicted co-conspirator in special counsel Jack Smith's federal election interference case against Trump. Giuliani denied the allegations.

Giuliani was hospitalized last year after he sustained injuries, including a spinal fracture, in a car crash in New Hampshire. Giuliani’s vehicle was “struck from behind at high speed” while he was riding as a passenger.

Trump said days after the accident that he would award Giuliani the Presidential Medal of Freedom.