TALLAHASSEE, Fla. (AP) — U.S. Sen. Bill Nelson isn't backing down from comments that Russian operatives have penetrated some of his state's election systems ahead of this year's crucial election.

Nelson on Monday evening said that it would be "foolish to think" the Russians are not continuing their efforts to target Florida. Russian hackers targeted at least 21 states, including Florida, ahead of the 2016 election. He said criticism of his comments are for "partisan political purposes."

Nelson said last week that Russians were able to get inside the election systems of "certain counties" and "now have free rein to move about."

Gov. Rick Scott demanded that Nelson provide proof, and suggested that the senator was either making it up or releasing classified information. Scott is challenging Nelson in this year's election.