Protesters believe Sessions' resignation will lead to the undoing of Special Counsel Robert Mueller's investigation into alleged collusion between Russian Federation and the Trump presidential campaign.
Sessions, who was an early backer of the Trump campaign, recused himself in March 2017 from overseeing the Russian Federation investigation under a similar rule which prohibits officials from overseeing investigations into subjects with whom they have a "a personal or political relationship".
Prosecutors are also waiting for Mr. Trump's legal team to return answers to Mr. Mueller's questions, CNN said. It's a job he knows well given that Whitaker has spent the previous year as Sessions' chief of staff.
The Democrats, who won the House in the mid-terms, have vowed to protect it. He has previously suggested drastically reducing the budget of Mueller's special counsel probe, in order to thwart Mueller's threat to the president's constitutional mandate.
Trump has made it clear, Swalwell said, that the only thing he cares about with the Justice Department and who runs it is "that person's position on his personal criminal exposure and that of his family in the Russian Federation probe".
Whitaker will oversee the Mueller investigation.
To this point, Trump has heeded advice not to directly interfere, though a new chapter in the relationship with the probe may have begun with the appointment of Matthew Whitaker as new acting attorney general.
Democrats said they feared the decision to appoint Mr Whitaker was the prelude to a decision by Mr Trump to terminate the investigation by Mr Mueller, which the president has constantly described as a "witch hunt". Even if Whitaker, Sessions' former chief of staff, does not curtail the investigation, Trump could direct him to take a more aggressive stance in declassifying documents that could further undermine or muddle the probe, the White House aide and Republican official said.
It wasn't clear immediately why Trump chose the hours after midterm results to fire Sessions.
House Democrats said on Wednesday that they would attempt to include a measure protecting Mueller into an appropriations bill that Congress is due to consider later this year.
You reported today that that doesn't seem likely, that recusal.
He questioned Deputy Attorney General Rod J. Rosenstein's ability to give Mueller such wide latitude and wanted to explore the bounds of what Mueller was examining, though Rosenstein kept Session's office "walled off" from the matter, this person said. "There is no mistaking what this means, and what is at stake: this is a constitutionally perilous moment for our country and for the president". But Mr Sessions's replacement will have the power to do so, or end the inquiry.
Rosenstein no longer will oversee the special counsel investigation. "By forcing the firing (of) the attorney general, the president now threatens the rule of law itself".
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 US official who has worked with Sessions and frequently talked with him.
In piercing attacks, Trump called Sessions weak and beleaguered.
-With assistance from Steven T. Dennis.