While Tallahassee Mayor Andrew Gillum was managing the city's response to a hurricane of historic proportions, his supporters were engaged in a separate storm because of a negative campaign ad lobbed by backers of the Democrat's gubernatorial opponent, Ron DeSantis.

With Hurricane Michael barreling toward Florida's Big Bend and Panhandle regions, the Republican Party of Florida unleashed a caustic television ad declaring Gillum is “running for governor and also from the FBI.”

While the city of Tallahassee has been the focus of a long-running federal investigation, Gillum has insisted he is not a target of the FBI probe into possible public corruption. The mayor has severed his friendship with Adam Corey, a lobbyist who appears to be at the center of the investigation. Among other things, Republicans have drawn attention to a trip to Costa Rica in which Gillum paid cash for his share of a rental house shared with Corey and others.

In the ad that ran as Michael left hundreds of thousands of Northwest Florida residents and businesses without electricity, Republicans called Gillum “not just radical but corrupt.”

The ad drew the wrath of Democrats throughout Wednesday and Thursday, with Gillum's campaign asking TV stations to yank it.

“It is abundantly clear that Congressman DeSantis is a liar who has no respect for Floridians and no positive vision for our state,” Johanna Cervone, a Gillum spokeswoman, said in a statement.

Also Thursday, a number of former prosecutors held a conference call with reporters castigating Republicans for the “shameful” spot.

Miami Beach Mayor Dan Gelber, a former federal prosecutor, rebuked Republicans for running “untrue ads” in areas where panicked Floridians were “glued to their TVs” in preparation for the storm, which devastated coastal communities such as Panama City and Apalachicola.

Gillum is a witness who has cooperated with the FBI in the public corruption probe, Gelber, a former state senator, said.

“It should be abundantly clear to people that DeSantis has become the say-anything and do-anything candidate,” Gelber said of the former congressman whose early endorsement by President Donald Trump helped the Republican cruise to victory in the August gubernatorial primary.

The GOP yanked the ad, which sparked a firestorm on social media, as Michael continued to spread havoc in Northwest Florida.

“As we stated earlier today, the order to take the ads down in the affected areas was made. Any statement to the contrary is simply wrong,” Republican Party of Florida spokeswoman Meredith Beatrice said in a email blast Wednesday.

Jim Turner and Dara Kam report for the News Service of Florida.