Nothing provokes the anger of the fiery and unconventional president more than special counsel Robert Mueller's investigation into whether his campaign colluded with Russian agents during his 2016 election.
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".
A website set up by MoveOn.org Political Action says Trump "crossed a red line, violating the independence of the investigation" Wednesday, when Sessions handed in his letter of resignation, reportedly at Trump's urging.
"The chances of Mueller being interfered with goes up dramatically" with Whitaker's appointment, he said.
While calling on Whitaker to recuse himself from the probe, Galland also said that "Congress must immediately move to protect the independence of Special Counsel Mueller and put in protections that prevent Trump from firing him or undercutting his investigation or having his new acting attorney general or eventual replacement obstruct Mueller's work".
As part of Whitaker's new role as the head official at the Justice Department, he will oversee the Russian Federation probe and the agency's other federal investigations, including the NY prosecutors' look into the finances of Trump and his former aides.
Democrats have slammed Whitaker's appointment to replace Sessions, arguing that Trump is trying to undermine Mueller and demanding that Whitaker recuse himself from supervising the Mueller investigation due to his writings and public comments attacking the investigation.
Sen. Lindsey Graham (R-S.C.) once vowed that there would be "holy hell to pay" if President Donald Trump ever fired Attorney General Jeff Sessions. Senate Minority Leader Chuck Schumer said that "protecting Mueller and his investigation is paramount".
Supreme Court Justice Ruth Bader Ginsburg Hospitalized After Fall
Fans of Notorious RBG , as she is sometimes known, immediately launched into grief - and action. "I'm now 85", Ginsburg said . But Ginsburg, the court's oldest sitting justice, has consistently been adamant that she has had no intentions of retiring.
After starting his career in private practice, Whitaker first ran for office in 2002, losing a race for state treasurer to longtime Democratic incumbent Michael Fitzgerald.
Meanwhile, President Donald Trump's legal team has begun working with the president to craft responses to questions from Mueller's team as part of their investigation, sources close to Trump told ABC.
Before Trump gave a news conference on Wednesday, White House Chief of Staff John Kelly called Sessions and told him that Trump wanted him out, the official said.
Jerry Role, a retired Department of Justice staffer told Al Jazeera that Trump's actions this week threatened the integrity of United States democracy.
CNN reports that Florida Attorney General Pam Bondi is also under consideration. 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.
According to U.S. media reports on Thursday, Mueller's team have started writing the final report of the investigation.
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.