Mr Whitaker has publicly criticised Mr Mueller's conduct several times since the inquiry began in May previous year and taken the side of President Trump, who has frequently...
Angus King expressed uncertainty Thursday about the effect on special counsel Robert Mueller's investigation into Russia's potential interference in the 2016 US presidential campaign.
Sessions has long faced criticism from Trump for recusing himself from Mueller's investigation of Russia's alleged meddling in the 2016 presidential election.
House Democratic leader Nancy Pelosi called it a "blatant attempt" to undermine the Russian Federation probe, while Senate Democratic leader Chuck Schumer tweeted that "clearly, the president has something to hide".
When the Democrats take over the House, they are expected to launch numerous probes of Trump, his business interests and his administrations. He has been rebuilding his relationship with Trump and senior White House officials during the presidency.
Hence, the timing of what Trump tweeted on Wednesday struck many as conspicuous.
According to two people familiar with Sessions's thinking who spoke to Politico, the former attorney general - who left his 20-year Senate career to be publicly mauled by President Trump for two years - is considering running for his old seat in 2020. Cox was eventually fired by the United States solicitor general. "A permanent replacement will be nominated at a later date", Mr Trump tweeted.
He could also refuse to sign off on a subpoena of Trump if the president refuses to voluntarily speak to investigators.
A day after Attorney General Jeff Sessions' forced resignation, independent U.S. Sen. "We have operated with integrity and have lawfully and aggressively advanced the policy agenda of this administration".
The Justice Department did not directly answer whether Whitaker would assume control of Mueller's investigation, with spokeswoman Sarah Isgur Flores saying he would be "in charge of all matters under the purview of the Department of Justice".
The Mueller investigation has so far produced 32 criminal charges and four guilty pleas from Trump associates.
Democrats see this latest move as an attempt to do just that.
Deputy Attorney General Rod Rosenstein took over supervision of the Russian Federation investigation.
He called for Deputy Attorney General Rod Rosenstein, who appointed Mueller and who has been supervising his work, to curb the investigation.
The investigators can pass their evidence to federal prosecutors in other jurisdictions outside the special counsel's authority, making it harder for Whitaker to block new indictments.
And, if nothing else, having an attorney general who isn't recused from Mueller's work might give the White House a clearer look inside it. "He was an egregious violator of civil rights and civil liberties", the ACLU statement said.
In attacks delivered on Twitter, in person and in interviews, 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 look into those claims.
CBS News has learned former New Jersey Gov. Chris Christie is being considered to replace Jeff Sessions as attorney general.