(CNN) Florida Democratic governor nominee Andrew Gillum's campaign is demanding television stations in Florida stop running an ad paid for by the Florida Republican Party that directly ties Gillum to an active FBI investigation.

There is an ongoing federal investigation into public corruption in Tallahassee. Gillum, who is the Tallahassee mayor, has said publicly that the FBI told him he was not a focus of the investigation.

The ad, in support of the GOP nominee for governor, Ron DeSantis, dropped late Tuesday night right before Hurricane Michael was poised to hit North Florida and the state's panhandle. The ad ran in markets directly impacted by the storm.

The letter from Gillum's campaign was sent to an undisclosed number of station managers by Glenn Burhans, Jr.,an attorney for the campaign. In the letter, Burhans says the ad is "demonstrably false in numerous respects and has been made with actual malice." He adds, "Mayor Andrew Gillum and the Gillum for Governor Campaign will take all available legal recourse to prevent the spread of the false and defamatory Advertisement."

Neither the DeSantis campaign nor the Florida Republican Party responded to requests for comment on the substance of the ad or the Gillum call for it to be taken down.

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