"It is impossible to read Attorney-General Sessions' firing as anything other than another blatant attempt by (Mr Trump) to undermine and end Special Counsel Mueller's investigation", House minority leader Nancy Pelosi wrote on Twitter.
Trump named Sessions' chief of staff, Matthew Whitaker, as acting attorney general, saying he would soon nominate a permanent replacement for review by the Senate.
He added that Trump's main problem with Jeff Sessions, whose resignation the president eventually demanded, was because the former senator had recused himself from the Russian Federation investigation, and not that he did "anything wrong or anything on immigration or national security or any other issue".
"We will not allow Trump to get away with obstructing this criminal investigation, and we will not allow Congress to abdicate its responsibility under the Constitution". He has, for instance, talked down the Mueller investigation on a number of TV talk shows.
The Nobody Is Above the Law network demands that Whitaker immediately commit not to assume supervision of the investigation. Whitaker also said the probe should not extend to the finances of Trump, his family or their business.
One reason Sessions endured months of taunting from Trump is that he believed he was protecting the integrity of the Justice Department and was trying to prevent the president from bringing in someone who would politicize it, according to a USA official who has worked with Sessions and frequently talked with him.
Democratic Rep. Jerrold Nadler, who is expected to chair the House judiciary committee starting in January, said removing Sessions fit Trump's pattern of interfering in the work of the justice department and Mueller.
"The president wanted to take action as quickly as possible in the Mueller investigation", said Sen.
"We can not let this president tell Bob Mueller what to do", Durkan, a former USA attorney, said before leading the crowd in a chant of "Let Bob do his job". The agency did not announce a departure for Rosenstein, who appointed Mueller and has closely overseen his work.
In an effort to keep the investigation independent, demonstrators around the country began protesting Thursday, Nov. 8 at 5 p.m. local time.
"I was anxious someone wouldn't stand up", Viola said.
The White House is bracing for the probe of Donald Trump's presidential campaign to fire up again.
The swift firing may have also been a way for Mr Trump to get ahead of any efforts from the newly-empowered Democrats to reopen the House intelligence committee's investigation into ties between Mr Trump's campaign team and Russian Federation.
As reason for his recusal, Sessions cited news reports of two undisclosed meetings he had with Sergey Kislyak, then Russia's ambassador to Washington. Justice Department officials said his taking over for his boss was, at the very least, "awkward", because chiefs of staff typically leave with the attorney general.
The Justice Department has declined to answer whether ethics officials have been asked to review if Whitaker should recuse himself from the Mueller probe.