Deputy Attorney-General Rod J. Rosenstein also generated a lot of buzz but little clarity with a statement urging Americans to "exercise caution" when evaluating stories attributed to anonymous officials.
He added: "Americans should be skeptical about anonymous allegations".
But there was some evidence that Rosenstein's motivation may instead have been his own mounting frustration at seeing details of the law enforcement investigation appear almost daily in the news media.
Accompanied by First Lady Melania, he will make his first trip to the Camp David presidential retreat in Maryland.
The Democratic National Committee called on Mr Rosenstein to recuse himself from the Russian Federation matter, but it said authority over the investigation should be given to Mr Mueller and not another Trump appointee.
Rosenstein, the deputy attorney general, had written a memo castigating James Comey before Trump dismissed the Federal Bureau of Investigation director - a memo that the White House at first said was critical to the decision, before Trump suggested it was irrelevant because his mind was already made up.
Rosenstein also wrote a memo recommending the dismissal of Comey for his mishandling of the announcements about and the FBI investigation into Democratic presidential candidate Hillary Clinton's use of a private email server when she was secretary of state.
The Staggering Hypocrisy of Newt Gingrich
Former House Speaker Newt Gingrich accused special counsel Robert Mueller on Thursday of trying to destroy, undermine and cripple Donald Trump's presidency.
He also said it would be up to Mr Mueller to decide whether Mr Trump's action amounted to obstruction of justice, an act that could be cited in any effort in the Republican-led Congress to impeach him and remove him from office.
Friday's tweets are the latest in a week of angry social media responses by the president over a report by The Washington Post that Mueller was looking into whether Trump obstructed justice.
Trump's apparent attack on Rosenstein also raised further questions about whether he will stay in his position or recuse himself from the investigation. The tweet comes amid reports that Trump may want to fire Mueller, which only Rosenstein is legally able to do. "However, nothing has changed".
I am being investigated for firing the FBI Director by the man who told me to fire the FBI Director!
Texas Sen. Ted Cruz said: "Bob Mueller is a good and honorable man, but I certainly hope that the appointment of a special counsel doesn't turn into a fishing expedition".
According to the Washington Post and the Wall Street Journal, Ledgett compiled a memo in which he retold the contents of Trump's telephone conversation with Coates, in which the president asked publicly state that his campaign headquarters was not colluding with Russian Federation. An official of Trump's transition confirmed the lawyer's internal order, which was sent Thursday. The memo asks for preservation of electronic communications and data, telephone logs, audio recordings, videos, calendars and other items. At a later meeting, Trump said he hoped Comey and the FBI would "let go" of the investigation into former National Security Adviser Michael Flynn's ties to Russian Federation. Those associates include former national security adviser Michael Flynn, campaign chairman Paul Manafort, foreign policy aide Carter Page and outside adviser Roger Stone.
The Justice Department on Friday said any such of consideration of recusal was premature.
"With this in mind", the memo said, "please immediately suspend any deletion, modification, overwriting, or other possible destruction of the information described above, including electronic information, and take all reasonable measures to preserve this information".