In a preview of the opposition Trump can expect in January, when a new Democratic majority takes control of the House of Representatives, the Democrats said Whitaker should not have been appointed because he has not been confirmed by the Senate.
The president later tweeted that Mr Mueller and "his gang of Democrat thugs" were destroying people, and blamed social media tech giants for unfavourable coverage towards his administration and the Republicans.
The president later tacked on: "The only "Collusion" is that of the Democrats with Russian Federation and many others. They have found no collusion and have gone absolutely nuts", Trump said on Twitter Thursday.
Congressional Democrats on Thursday dismissed as "fatally flawed" a Justice Department legal opinion defending Trump's decision to appoint Whitaker as acting attorney general to replace ousted Jeff Sessions.
Obama memoir 'Becoming' released as part of $60M book deal
As a whole, it painted a picture of the country as one where everyone counts and Obama's repeated mantras sounded like a chant. Obama admitted she first got the idea to pay it forward from Bush, who had given her the same offer for help.
The diatribe came amid claims that Trump is maneuvering to have Mueller fired or otherwise shut down before he can close in on the president and his inner circle, including family members. "Why is he protecting Crooked Hillary, Comey, McCabe, Lisa Page & her lover, Peter S, and all of his friends on the other side?" he wrote, referring to fired Federal Bureau of Investigation director James Comey, former anti-Trump agent Peter Strzok, and fired Deputy Director Andrew McCabe.
Mueller reported to Rosenstein until November 7, when Whitaker took over the probe. They still don't have it. Mueller is a registered Republican who was confirmed as head of the Federal Bureau of Investigation under former President George W. Bush and continued serving until 2013, during Obama's second term. Check out how biased Facebook, Google and Twitter are in favor of the Democrats.
"It's been nearly a week since we called on Matthew Whitaker to recuse himself from overseeing the Special Counsel Investigation".
Democrats are concerned that Whitaker, who has previously expressed concern about the scope of the Mueller probe, may limit or end the Russian Federation investigation.
The American Constitution Society on Wednesday released a powerful letter signed by at least 1,600 attorneys nationwide calling for lawmakers and Justice Department officials to protect the Mueller probe. Senator Lindsey Graham (R-SC), curiously enough, recently broke his newfound blind loyalty to President Trump by supporting such a bill.