Since then, Whitaker, who had been Sessions' chief of staff, has faced pressure from Democrats to recuse himself from overseeing special counsel Robert Mueller, based on critical comments he made about the investigation before joining the Justice Department previous year.
Sessions was the first and perhaps most enthusiastic sitting senator to endorse Trump's presidential campaign, but his departure comes as no surprise. But the end result was, by any measure, a foregone conclusion.
David Bosel, a retired political scientist, described Trump's attempts to scupper the Mueller investigation as "dictatorial" and accused most Republicans in Congress of helping Trump tilt the USA towards "fascism". Whitaker very vocally believes otherwise.
"To be U.S. Attorney, that's top of the line", Trump said.
Thanking Sessions for his service, Romney said that it was "imperative that the important work of the Justice Department continues, and that the Mueller investigation proceeds to its conclusion unimpeded".
Spats between Trump and journalists can sometimes seem circus-like, but critics say the president's hot temper illustrates his deeper disdain for Washington norms - and allegedly for the rule of law.
"I think this will be a very interim AG", McConnell said.
Trump has repeatedly criticized Sessions for that decision, and the Attorney General's dismissal has been expected for a long time.
Whitaker's argument, a common one among Trump supporters, completely misses the point of what obstruction of justice is. Whitaker, who was serving as chief of staff for Sessions, was not serving a post that required Senate confirmation.
A large crowd gathered near Philadelphia City Hall on Thursday evening in support of protecting the Mueller investigation, a day after Attorney General Sessions was forced out.
"I'm profoundly concerned about it", he said.
Some legal scholars - including George Conway, the husband of Trump counselor Kellyanne Conway - said they thought Whitaker's appointment is unconstitutional because he is not a Senate-confirmed official.
Since stepping into his new role on Wednesday, Whitaker has faced questions - principally from Democrats - about whether he should recuse from the Russian Federation investigation, given that he has written opinion pieces in the past about the investigation, and is a friend and political ally of a witness.
The US President fired Sessions after he had been critical of him for failing to stop the Russian Federation investigation.