Senior Republicans have warned President Trump against trying to impede the long-running inquiry into Russian interference in the 2016 election after he named a critic of the investigation as his acting attorney-general.
But its fate now depends on the acting Attorney General Matt Whitaker - who's been openly critical of the investigation.
Trump said he will nominate a permanent successor for Sessions at a later date.
Trump had repeatedly been talked out of firing Sessions until after the midterms, but he told confidants in recent weeks that he wanted Sessions out as soon as possible after the elections, according to a Republican close to the White House who was not authorized to publicly discuss private conversations.
He also once tweeted a prosecutor's opinion piece that described the Mueller team as a "lynch mob", and wrote his own op-ed saying Mueller would be outside his authority if he investigated Trump's family finances.
"I am not concerned about anything with the Russian investigation, because it is a hoax", he said.
However, with Republicans tightening their grip on the Senate, an initially magnanimous-sounding Trump suggested that a divided Congress would bring opportunity for bipartisan cooperation - something in low supply in Washington.
At a protest in support of Mueller outside the White House, a crowd of several hundred protesters shouted anti-Trump slogans.
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The British star has played police officer-turned-survivor Rick Grimes in the post-apocalyptic USA series since its inception in 2010.
Only minutes later, a series of questions he found overly hostile sent him into a most un-loving blowup.
Sessions took the lead in imposing Trump's travel ban targeting a number of mostly Muslim nations, canceling the so-called Dreamer program that let the children of undocumented immigrants remain in the USA and forcing the separation of migrant families as part of a border crossing crackdown.
Progressive activists denounced Whitaker as a political operative.
"The question is: did the reporter make contact or not?"
Experts say, however, that any investigation into the role foreign countries play in domestic politics must delve down financial rabbit holes.
The relentless attacks on Sessions came even though the Alabama Republican was the first US senator to endorse Trump and despite the fact that his crime-fighting agenda and priorities - particularly his hawkish immigration enforcement policies - largely mirrored the president's.
In April, Pingree co-sponsored House legislation to protect the Mueller investigation by making it more hard for a president to remove a special counsel. Mueller is looking into whether anyone on that campaign might have conspired with the Russians who attacked the 2016 election.
"It was supposed to be on collusion".
Des Moines attorney Guy Cook, a Democrat who has known Whitaker for years, called him a clear thinker and a "no-nonsense guy who is not to be underestimated". "I believe they would". "I'm saddened by the way people vote and where the country has gone".