Little noticed at the time, Vladimir Putin's guests that night included Flynn and future Green Party presidential candidate Jill Stein-an odd couple who reflected the Russian president's efforts to court fringe figures on both the right and the left and otherwise meddle in United States politics.
Included in those options is the possibility of holding Flynn in contempt of Congress for refusing to cooperate with the investigation.
Warner, a Virginia Democrat, also told Bash that if reports that Trump asked top intelligence officials to publicly deny evidence of cooperation between his campaign and Russian Federation are true, Trump's requests would be "outrageous".
"In these circumstances, (Flynn) is entitled to, and does, invoke his Fifth Amendment privilege against production of documents", Flynn's lawyer wrote in a letter to the committee, verified by CNN. They also said earlier in the day that the Justice Department's appointment of a special counsel has created a legally risky environment for him to cooperate with the Senate panel's investigation.
The Senate committee's subpoena to Flynn focused on his interactions with Russian officials.
The House intelligence panel, meanwhile, is requesting documents from former Trump campaign communications adviser Michael Caputo.
Flynn's attorney declined multiple requests for comment Monday from ABC News.More news: House Intelligence Hearing With John Brennan
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Gen Flynn, a retired US Army lieutenant general and former director of the Defense Intelligence Agency, was a top adviser to Donald Trump's presidential campaign.
Rep. Adam SchiffAdam SchiffHouse Intel panel likely to also subpoena Flynn businesses, Dem says Ex-CIA head: Intel showed contacts between Russians and Trump team Trump asked intel chiefs to speak out against FBI's Russia probe: report MORE (D-Calif.) said the House panel is considering similar measures.
On Monday, Cummings said Flynn provided inconsistent or misleading statements to US security clearance investigators in the first three months of 2016 during the renewal of his credentials. However, Cummings points to Flynn having sat next to Russian President Vladimir Putin and received $45,000 to attend an event hosted by Russian television network RT. Flynn has since been implicated in offering misleading answers about his Russian Federation contacts to the Pentagon when he applied to renew his security clearance past year and could face charges for failing to file as a foreign agent after accepting more than $500,000 for representing Turkish interests.
Warner explained the importance of continuing the Senate investigation even in light of the Justice Department's decision. The former Federal Bureau of Investigation director agreed to testify before the Senate intelligence committee after the Memorial Day holiday.
This information surfaced shortly after Trump had fired Comey.
The refusal to comply risked Flynn being cited for contempt of Congress. The committee would have to notify the attorney general before applying for an immunity court order.
The American Constitution says in its Fifth Amendment that no person "shall be compelled in any criminal case to be a witness against himself".
Briefing reporters following a closed-door intelligence meeting on Tuesday, Sens.