Michael Grimm, a former U.S. representative from Staten Island, was paralyzed after a fall from a horse during a polo competition in September. The condition of Mr. Grimm, a Republican and former F.B.I. agent and Marine who resigned from Congress in 2015 and served seven months in prison for tax fraud, was first reported by a colleague from Newsmax, where Mr. Grimm had found a second career as an on-air personality.

The colleague, Greg Kelly, said on his radio show that the accident happened during a polo tournament on Sept. 22. He required emergency surgery, Mr. Kelly said.

“He’s a great horseman, and he was thrown from the horse and seriously damaged his neck,” Mr. Kelly said on the program. “Please say a prayer.”

Vincent Ignizio, a former city councilman from Staten Island and a friend of Mr. Grimm, said the former representative was paralyzed from the chest down.

Mr. Grimm, who first won election to the House in 2010, was indicted in 2014 after failing to report nearly a million dollars in gross receipts from a restaurant he had owned in Manhattan called Healthalicious, and lying about it under oath.

After winning re-election later that year, he pleaded guilty to felony tax evasion and resigned his seat representing the 11th Congressional District, which includes Staten Island and a part of Brooklyn, in January 2015. He was later sentenced to eight months in prison, serving seven.