The federal government is prepared for an onslaught of foreign hackers to accost U.S. voting systems on Election Day, the head of the FBI said Tuesday.

Officials are taking the threat "very, very seriously," FBI Director James Comey said in remarks at the Symantec Government Symposium in Washington. "We take very seriously any effort by any actor to influence the conduct of affairs in our country, whether that's an election or something else."

The remarks follow a Monday report that hackers targeted voting systems in Arizona and Illinois. The attack on Arizona was unsuccessful, though they did manage to make off with information on 200,000 voters in Illinois.

In a Friday letter delivered to Comey, Democratic Senate Minority Leader Harry Reid singled out the Russian government as a threat he hoped officials would defend against. "The threat of the Russian government tampering in our presidential election is more extensive than widely known and may include the intent to falsify official election results," Reid suggested.

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The basis for Reid's statement was not entirely clear since the intelligence necessary to attribute responsibility to Russia is classified. In Congress, clearance to view that information is available exclusively to members of the armed services and intelligence committee, as well as some members of leadership.

Democrats have sought to attribute responsibility for a spate of hacks over the summer to Russia in an effort to impugn Republican presidential nominee Donald Trump. The party has argued that Trump has been too soft in his rhetoric concerning Russian President Vladimir Putin and that it has resulted in that country seeking to target U.S. electoral infrastructure.

The Obama administration has been less willing to attribute culpability. Director of National Intelligence James Clapper said in July he was "taken aback" by "hyperventilation" over the issue, while CIA Director John Brennan said observers were "jumping to conclusions."