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Top Democrats on four House committees that oversee national security on Friday called on the FBI to investigate Donald Trump's purported ties to the Russian government and its alleged hacking of Democratic groups and operatives.

“Troubling new evidence appears to show that the Trump campaign not only was aware of cyber attacks against Secretary Clinton’s campaign chairman, but was openly bragging about it as far back as August,” read a joint statement from Reps. Elijah Cummings, John Conyers, Elliot Engel and Bennie Thompson, who are respectively the ranking members of the House Committees on Oversight and Government Reform, Judiciary, Foreign Affairs, and Homeland Security.

“For months, we have been asking the FBI to examine links between the Trump campaign and illegal Russian efforts to affect our election,” the Democrats’ statement continued. “In light of this new evidence -- and these exceptional circumstances -- we call on the FBI to fully investigate and explain to the American people what steps it is taking to disrupt this ongoing criminal activity.”

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The Trump campaign did not immediately respond to a request for comment.

The lawmakers specifically cited Trump confidant Roger Stone, who tweeted in August that Clinton campaign chairman John Podesta would soon be “in the barrel.” WikiLeaks last week began releasing the contents of Podesta’s personal email account, which U.S. officials say was likely hacked by Russian government operatives.

Related: Roger Stone Calls Claims of WikiLeaks Collusion 'Categorically False'

But Stone told NBC News this week that while he has had “back-channel communications with WikiLeaks,” it was “categorically false” to say he was coordinating with the group or that he had any connections to the Russian government.

Trump continues to highlight the Wikileaks dumps during campaign events, saying earlier this week in Pennsylvania, “I love WikiLeaks.”

Meanwhile, Hillary Clinton’s campaign has been trying to raise the alarm about what they call Russian government sponsored hacking intended to boost Trump.

Former CIA Director Michael Morell said on a conference call organized by the Clinton campaign Friday morning that he was “100 percent confident” that the Russian government was behind the Podesta hack, calling it “a direct assault on our democracy.”

“Trump continues to play to Putin's hand almost every single day,” Morell added.

FBI Director James Comey said in congressional testimony in late September that he was aware of Democrats’ call for an investigation but that he would not “confirm whether there is or is not an investigation.”