Democratic Representative Jerry Nadler, who will likely become chairman of the House Judiciary Committee - which has congressional oversight over the Mueller probe - immediately responded to Sessions' resignation by demanding an explanation for the change.
The President was furious when Mr Sessions recused himself from investigations into Russia's possible meddling in United States elections and collusion with the Trump campaign, paving the way for the appointment of Special Counsel Robert Muller. And while Sessions' departure could jeopardize the Mueller investigation, the news also has cannabis advocates celebrating like the Ewoks after the destruction of the Death Star.
On Capitol Hill, Senate Minority Leader Chuck Schumer (D-N.Y.) said "Protecting Mueller and his investigation is paramount".
Schumer, of NY, expressed concern over the choice of former southern Iowa federal prosecutor Matt Whitaker as Sessions replacement.
Instead, he gave Deputy Attorney GeneralRod Rosenstein the authority to oversee the probe independently.
In August 2017, roughly a month before his appointment as Sessions' chief of staff, Whitaker penned an op-ed for CNN in which he suggested the Russian Federation investigation was "going too far" and could be "a witch hunt".
"[Whitaker] will serve our Country well", Trump tweeted.
In an opinion piece for CNN published in August 2017, he wrote: "Mueller has come up to a red line in the Russian Federation 2016 election-meddling investigation that he is dangerously close to crossing".
Democrat Senator Chuck Schumer has warned "any attorney-general ... should not be able to be able to interfere in the Mueller investigation in any way".
"This may be the first step in President Trump's attempt to fire Special Counsel Robert Mueller", Noah Bookbinder, executive director of Citizens for Responsibility and Ethics in Washington (CREW), said in a statement after Sessions' ouster on Wednesday. "But when everybody sees what's going on in the Justice Department - I always put "justice" now with quotes".