The forced resignation of Jeff Sessions as attorney general has caused profound leadership changes at the Justice Department, above all affecting oversight of the investigation into ties between President Donald Trump's campaign and Russian Federation.
Overseeing it all is Whitaker, a former college football player and United States attorney from Iowa who was brought into the Justice Department a year ago to serve as Sessions' chief of staff.
Through his CNN role, where he was deeply critical of the Mueller probe, Whitaker got to know Trump, who saw him on TV and later met in person. "That's why Cabinet Secretaries have Deputies".
Mr Sessions' firing immediately threw into question whether the 18 month old Mueller probe will be able to continue unimpeded.
The special counsel's team has been investigating Stone's connection to WikiLeaks during the 2016 campaign and whether he had advance knowledge of the group's plans to release hacked material damaging to Democrat Hillary Clinton.
He also said the line of succession within the Justice Department does not include the chief of staff and the fact that someone in that position would be made acting attorney general is "very odd".
White House emphasizes continuity and not disruption with Sessions' resignation.
Whitaker received a law degree from the University of Iowa and then worked in private practice before being appointed in 2004 by then-President George W. Bush to serve as US attorney for the Southern district of Iowa.
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And the Justice Department acknowledged in Monday's request that the appeals court ruling is likely to come first. That is the lead case that the Administration appealed to the Justices on Monday.
According to legal analysts cited by The Guardian, Trump's decision may set off a constitutional crisis over the fate of the Mueller inquiry, which followed a conclusion by United States intelligence agencies that Russian Federation intervened to help Trump win in 2016.
Democrats poised to take charge of House committees come January are signaling that they want to investigate the replacing of former Attorney General Jeff Sessions with Acting Attorney General Matt Whitaker.
A spokesman for Mueller's office declined to comment on Sessions' departure.
Jerry Role, a retired Department of Justice staffer told Al Jazeera that Trump's actions this week threatened the integrity of U.S. democracy. And since Sessions technically resigned instead of forcing the White House to fire him, he opened the door under federal law to allowing the president to choose his successor instead of simply elevating Rosenstein, said University of Texas law professor Stephen Vladeck.
Whitaker is expected to assume oversight of Mueller's Russian Federation investigation.
"We'll see what happens over the next few days, but it is a concern because (Preisdent Donald Trump) obviously was unhappy with Jeff Sessions because of his recusal, but Jeff Sessions did what the law required him to do", King said in an interview at the school.
But Senate Judiciary Chairman Chuck Grassley praised Whitaker. His style rubbed many the wrong way, and at times Justice Department officials pushed back on his demands. "A permanent replacement will be nominated at a later date".
Sessions, 71, has a long political history in Alabama.
Sessions took the lead in imposing Trump's travel ban targeting a number of mostly Muslim nations, canceling the so-called Dreamer program that let the children of undocumented immigrants remain in the US and forcing the separation of migrant families as part of a border crossing crackdown.