In a joint statement Wednesday evening, Senator Richard Burr (R-North Carolina), the committee chairman, and Senator Mark Warner (D-Virginia), the vice-chair, stated that the Senate Select Committee on Intelligence has issued a subpoena for Flynn.
The Senate Intelligence Committee issued the demand for documents from Flynn relating to Russia's alleged meddling.
McCabe further said Comey had "broad support" within the bureau, a comment that stands at stark odds with a White House defense of Trump's decision, namely that Comey "lost the confidence" of the bureau's rank and file.
President Trump fired him after he misled vice president Mike Pence about conversations he had with Russia's ambassador.
Flynn's Russian Federation ties are also being scrutinized by the FBI as it conducts a similar investigation.
The Intelligence Committee's subpoena comes the day after President Trump abruptly fired FBI Director James Comey, claiming Comey was no longer doing a good job.
Burr is one of several prominent Republicans who have expressed strong doubts about the timing of Trump's action.
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"Everybody's convinced: They say there is no collusion", Trump said.
Mr Flynn's Russian Federation ties are also being scrutinised by the FBI as it conducts a similar investigation.
Six top United States intelligence officials told Congress Thursday they agree with the conclusion that Russian Federation acted to influence last year's election, countering President Donald Trump's assertions that the hacking remains an open question.
The FBI and the Senate and House intelligence committees are each conducting their own investigations into potential links between associates of Donald Trump and the Kremlin.
"My White House counsel, Don McGahn, came back to me and did not sound like an emergency", Trump said.
But senior Democrats said he had recently asked the Justice Department for more resources for his Trump-Russia investigation. McCabe was testifying in place of former FBI Director James Comey, who was sacked by President Donald Trump on Tuesday.
The top Democrat and Republican on a House oversight committee have said that Flynn likely broke federal law by failing to get approval from the US government to accept foreign payments and not disclosing them after accepting them.