In an appearance on CNN, Sen. Sheldon Whitehouse (D-RI) told host Wolf Blitzer that he has compelling evidence to suggest President Donald Trump's disgraced national security adviser Mike Flynn is cooperating with the FBI and potentially has been "for some time".

The segment began as news broke that House Democrats are demanding documents from Flynn on information he allegedly left off of his security clearance disclosures, at which point Blitzer cut to Sen. Whitehouse of the upper legislative body's judiciary committee.

"All of the signals are suggesting that he's already cooperating with the FBI and may have been for some time," Whitehouse said.

According to Whitehouse, there are a number of reasons to believe Flynn is complying with the FBI, including the "holes" left in many of the most recent revelations about Trump and his associates' relations with Russia.

"All the subpoenas are one hop away from Flynn," Whitehouse said. "He's like the hole in a donut of subpoenas."

One of the subtler reasons to believe Flynn is working with the FBI, Whitehouse argued, is his uncanny silence in recent months.

"One of the more talkative people in Trumpland has gone absolutely dead silent," he concluded, "and that's what prosecutors strongly encourage cooperating witnesses to do."

Whitehouse said Flynn's potential cooperation with the FBI could have major implications for the investigation into Trump-Russia collusion.

"It could be a huge deal, because who knows what Trump has said to him, both during the campaign and during the early days of the presidency," Whitehouse said. "Apparently trump has been in touch with him after his firing from the White House to tell him to stay strong, which, in some circumstances, could be looked at as manipulation of a witness or obstruction of justice."

Watch the entire segment below via CNN.