The Attorney General, who was sworn in last week despite opposition from Democrats and civil rights activists, is now being asked to recuse himself from his role at the nation’s highest office after speculation is swirling that he may also have been involved in the Russia-related scandal.
That is despite revelations that Mr Sessions would lead the investigation against Mr Flynn.
The Trump campaign said in a statement on 7 October 2016 last year that his national security council included Mr Flynn, Mr Sessions, Republican Senator Tom Cotton and former Fox News anchor KT McFarland.
After earlier incorrect reports that she had also quit, Ms McFarland said she would remain in her role as the deputy national security adviser after Mr Flynn resigned.
Mr Sessions was reportedly a key architect of Mr Trump’s Muslim ban, which barred nearly all travellers from seven Muslim-majority countries for at least 90 days and indefinitely suspended Syrian refugees. The executive order was signed on 27 January, before Mr Sessions was sworn in to office.
He has long been a supporter of the President, and acted as an adviser. During his senate confirmation hearing, he said he would recuse himself from any investigation into Hillary Clinton and her alleged misuse of her personal email server when she was secretary of state as he had spoken against her during the campaign.
Senate minority leader Chuck Schumer said that there needs to be "an independent and transparent investigation into General Flynn’s action and the Trump’s administration’s knowledge of them".
"Gen Flynn’s resignation is not the end of the story, it is merely the beginning and the American people deserve to know the truth," he said.
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