He was formerly chief of staff to Jeff Sessions.
Less than 24 hours after the 2018 midterms drew to a close, Donald Trump has forced his first attorney general out of his administration, clearing the way for a man who has publicly accused Robert Mueller of taking the Russian Federation investigation "too far" - and mused that a new attorney general could thwart his probe by denying it funding - to become the Justice Department's interim leader.
"[Whitaker] will serve our Country well", Trump tweeted.
Embattled Attorney General Jeff Sessions resigned from his office on Wednesday morning after President Donald Trump requested he do so. "A permanent replacement will be nominated at a later date", the president wrote after sidestepping a question about Sessions' future during a wild press conference.
Though Mr. Sessions was the first senator to endorse the president in 2016, things began to sour once Mr. Sessions was ensconced at the department, and recused himself from Russian Federation investigation matters.
Whitaker added in the piece that "it is time for [Rod] Rosenstein...to order Mueller to limit the scope of his investigation".
Trump used a tweet Wednesday afternoon to make the announcement and install Matthew Whitaker, Sessions' chief of staff, as the acting attorney general.
Mr Trump has at various times belittled Mr Sessions as "beleaguered", "VERY weak", and "DISGRACEFUL". Whitaker is a former US district attorney from Iowa.
"Bob Mueller is totally conflicted", Mr Trump continued but provided no evidence that the team led by Mr Mueller, a Republican appointed by Republicans, is biased against him.
Whitaker, who will now oversee the Mueller investigation, wrote an op-ed for CNN.com in August, 2017, arguing the Mueller would be going too far if he were investigating Trump's finances. In that letter, Sessions explained, "we have restored and upheld the rule of law - a glorious tradition that each of us has a responsibility to safeguard".