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.
Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.