Federal authorities in Florida have issued an expansive subpoena seeking information related to Andrew Gillum, the former Tallahassee mayor, and the campaign for governor he narrowly lost last year, as well as some of his associates.

In a statement on Thursday night, Mr. Gillum’s lawyer, Barry Richard, acknowledged the subpoena but denied that Mr. Gillum had done anything wrong. “Somebody is out to damage Mr. Gillum politically and is making allegations to different law enforcement bodies,” he said.

The closely watched 2018 campaign — Mr. Gillum, a Democrat, would have been Florida’s first black governor — was shadowed by questions about corruption following a federal investigation into Tallahassee’s community redevelopment agency that resulted in three arrests.

Mr. Gillum has said that he was never a target of that investigation, in which undercover F.B.I. agents cozied up to a businessman with close ties to Mr. Gillum, eventually meeting the mayor on a New York trip that included a boat tour of New York Harbor. The recent subpoena was unrelated to Mr. Gillum’s time as mayor, Mr. Richard said.