Sessions, in a resignation letter to Trump, wrote that he was stepping down at "your request", accepting a fait accompli he'd long sought to avert despite Trump's repeated public humiliations of the attorney general over his recusal from oversight of the Russian Federation probe.
Never in modern history has a president attacked a Cabinet member as frequently and harshly in public as Trump did Sessions, 71, who had been one of the first members of Congress to back his presidential campaign in 2015.
But it's not typical for chiefs of staff to replace the head of an agency when that head resigns, as former CIA staffer and NBC contributor Ned Price pointed out.
Outcry from Democrats. Democrats viewed the move as a clear attempt to crush the Russian Federation election-meddling probe and called for Whitaker to recuse himself as Sessions had done, the BBC reports.
About six Congressional Democrats including Senators Bernie Sanders, Elizabeth Warren, Ron Wyden and Cory Booker stressed that Trump may be attempting to disrupt the Mueller investigation and called on Whitaker to recuse himself.
She said the investigation into alleged Russian Federation collusion has been winding down for weeks prior to Sessions stepping down.
"Sessions allowed the Department of Justice to function as the political arm of the Trump administration to undo fundamental rights that protect each of us, disregarding years of legal precedent and settled law".
FILE - Then-Iowa Republican senatorial candidate and former U.S. Attorney Matt Whitaker is pictured before a televised debate in Johnston, Iowa, April 24, 2014. But Trump and his aides are concerned about Mueller's next move with the work that is complete, according to a White House official and a Republican with close ties to the administration.
The Mueller investigation has so far produced 32 criminal charges and four guilty pleas from Trump associates.
Asked Wednesday if Whitaker would take control of the probe, Justice Department spokeswoman Sarah Flores said Whitaker would be "in charge of all matters under the purview of the Department of Justice".
While Sessions may be privately considering his options, Luther Strange, the man appointed to hold Sessions's seat until the 2017 special election is publicly urging the former attorney general to throw his hat in the ring.
"He worships him", a longtime friend said of Whitaker and Trump.
He found satisfaction in being able to reverse Obama-era policies that he and other conservatives say flouted the will of Congress, including by encouraging prosecutors to pursue the most serious charges they could and by promoting more aggressive enforcement of federal marijuana law.
Sessions endured most of the name-calling in silence, though he did issue two public statements defending the department, including one in which he said he would serve "with integrity and honor" for as long as he was in the job.
Sessions, who likely suspected his ouster was imminent, was spotted by reporters giving some of his grandchildren a tour of the White House over the weekend. He recused himself the next day, saying it would be inappropriate to oversee an investigation into a campaign he was part of.
A permanent replacement for Sessions must be confirmed by the Senate, which Trump's Republicans will continue to control as a result of Tuesday's midterm elections.
Sessions had been protected for much of his tenure by the support of Senate Republicans, including Judiciary Committee Chairman Chuck Grassley, who had said he would not schedule a confirmation hearing for another attorney general if Trump fired him. "I just know what I've read and that he was critical in the past of the special counsel's investigations, which obviously raises concerns", King said.