Florida officials want more information from the U.S. Senate supporting claims made by Sen. Bill Nelson that Russian operatives have penetrated some of his state’s election systems.

Florida Secretary of State Ken Detzner sent a letter requesting the information Thursday to Sen. Richard Burr, who chairs the Select Committee on Intelligence.

Citing the Intelligence committee as his source, Nelson told the Tampa Bay Times on Wednesday that operatives have “penetrated” certain counties in the state. He declined to identify the counties, saying it was classified.

Detzner’s letter says his office has no evidence to support Nelson’s claims. Detzner says he also reached out to federal law enforcement and was told they couldn’t corroborate the hacking claims either.

Nelson, a Democrat, is running for re-election this fall against Republican Gov. Rick Scott.

(AP)