The former attorney general submitted a letter of resignation at the president's "request". Senate Minority Leader Chuck Schumer said that "protecting Mueller and his investigation is paramount". Previously he was a conservative legal commentator who was critical of the scope of Mueller's probe.
"The forced firing of Attorney General Sessions appears to be part of an ongoing pattern of behavior by the president seeking to undermine (the) investigation into Russian interference", said the letter to Goodlatte, written by Representative Jerrold Nadler, the committee's top Democrat, and 16 other Democrats who sit on the panel.
In piercing attacks, Trump called Sessions weak and beleaguered, complained that he wasn't more aggressively pursuing allegations of corruption against Democratic rival Hillary Clinton and called it "disgraceful" that Sessions wasn't more serious in scrutinizing the origins of the Russian Federation investigation for possible law enforcement bias - even though the attorney general did ask the Justice Department's inspector general to examine those claims.
Whitaker also worked on Sam Clovis's failed campaign for Iowa state treasurer in 2014 after both of them ran unsuccessfully for the U.S. Senate. The moment the Democrats clinched the required 23 seats to retake the lower chamber; they were readying the various probes into this presidency-and the left wing harassment of this administration is about to begin.
"I'm profoundly concerned about it", he said.
It is unclear who Trump will ultimately replace Sessions with and how long Whitaker will serve as acting Attorney General.
In pushing out his attorney-general, the President cast aside one of his earliest and strongest supporters. Trump, who did not speak with Sessions himself, then ducked questions about Sessions' fate at the news conference. "I'm not recused, you're not recused", Conway told reporters.
Interested in Russia Investigation?
"Trump's actions are being compared with those of U.S. President Richard Nixon in one of the most controversial episodes of the Watergate scandal, the Saturday Night Massacre", said organizers.
He added that if the firing of Mr Sessions is not immediately investigated, the Democratic Congress would make it a priority when it is sworn in in January.
Whitaker was a hard-charging top aide to Sessions, imposing on the Justice Department his personal philosophy of starting with the end in mind.
By Thursday morning, more than 1,000 people said on a Facebook page for the event that they planned to attend, and more than 3,200 said they were interested.
Sessions clashed, though, with Jared Kushner, the president's son-in-law and senior adviser, resisting his proposals to overhaul the criminal justice system and standing by his hard-line approach to imprisonment and sentencing.