Gov. Rick Scott (R-FL) is demanding Sen. Bill Nelson (D-FL) provide proof to back up his statement that Russian operatives penetrated Florida’s election systems ahead of this year’s crucial election.

Scott, who is is running against Nelson in November’s midterm elections, during a campaign stop in Tampa, demanded his opponent provide “evidence for his claims,” of Kremlin-linked hackers infiltrating’s the state’s election systems. “This cannot be swept under the rug,” said Scott. “Bill Nelson must come clean and provide a thorough explanation. Elections are not something to try to scare people about.”

“Either Bill Nelson knows of crucial information the federal government is withholding from Florida elections officials, or he is simply making things up,” added Scott. “Did Nelson illegally release some classified information? Or did he make this charge of Russian penetration up?”

Nelson earlier in the week claimed that Russians were able to get inside the election systems of “certain counties” and “now have free rein to move about.” He added that “the threat is real and elections officials — at all levels — need to address the vulnerabilities.”

The senator, who is the ranking member of the cyber subcommittee of the Senate Armed Services Committee, has yet to provide additional details, alleging such information is classified.

Florida officials pushed back forcefully against Nelson’s comments, stating they had “zero information” to back up allegations of Russian election interference. Secretary of State Ken Detzner sent a letter to the chairman of the Senate Intelligence Committee demanding “immediate transparency and cooperation” in sharing any information about new hacking efforts.

When pressed on the matter, Nelson responded, “I hope the appropriate federal officials find a way to immediately provide them all the information they can to protect our elections.”

Department of Homeland Security spokesperson Sara Sendek said in a statement Wednesday: “While we are aware of Senator Nelson’s recent statements, we have not seen any new compromises by Russian actors of election infrastructure. That said, we don’t need to wait for a specific threat to be ready.”

Sen. Marco Rubio (R-FL), who serves on the Senate Intelligence Committee, co-wrote a letter with Nelson last month to all 67 of the county election supervisors in their state warning them of potential threats. Rubio on Friday put out a carefully worded statement wherein he did not confirm or deny Nelson’s allegations:

Given the importance of Florida in our national politics, our states election systems have been and will remain a potentially attractive target for attacks by foreign actors. While I firmly believe states should remain in the lead on conducting elections, the federal government should stand ready to assist as needed in confronting actual or potential attacks from determined foreign adversaries.

Rep. Tom Rooney (R-FL) issued his own statement, declaring he has seen “no evidence that Russians penetrated Florida’s election system.”

Russian hackers reportedly targeted at least 21 states, including Florida, ahead of the 2016 election and are believed to have breached the voter registration system in at least one, Illinois, according to investigators. An indictment released last month said that Russian operatives sent over 100 fake emails to elections offices and personnel in Florida as part of the hacking effort. State officials have never acknowledged how many counties were targeted by the Russians.

In May, Scott ordered the hiring of special election security consultants after Florida legislators rejected his request for nearly $500,000 to create a stand-alone cybersecurity unit in the Department of State. Legislators, however, did agree to set aside $1.9 million to provide grants to local election officials to purchase a security monitoring service. Ahead of this year’s election, Florida is also distributing more than $14 million in federal election security grants to local election officials.

The Associated Press contributed to this report.