Jennifer Palmieri, who worked in the Clinton administration and later on Hillary Clinton's presidential campaign, offered a dire warning for Trump aides on what could come in a White House facing the pressures of an investigation.
What will Robert Mueller do as special counsel?
Moments later Mr Trump added, "This is the greatest single witch hunt of a politician in American history!"
Thursday was not the first time Mr Trump has made baseless claims without providing any evidence.
Trump was speaking amid reports that he appealed to then FBI Director James Comey to shut down the bureau's investigation into former National Security Adviser Michael Flynn earlier this year.
Mr. Rosenstein did not go as far as he could have in granting Mr. Mueller autonomy - U.S. Attorney Patrick Fitzgerald was subject to less supervision from the Department of Justice when he was appointed special counsel to investigate the leaking of Central Intelligence Agency operative Valerie Plame's identity.
Trump lambasts 'witch hunt' after ex-FBI boss named Russian Federation probe chief
Mueller, he explained, will be "completely siloed off from the Department of Justice and the Federal Bureau of Investigation ". Flynn what the next step, if any, is". "'I think it could be' impeachable, Jones told POLITICO", the outlet reports .
"I expected him to be ranting and raving, but he was like, 'Fine, let them do what they have to do, but we'll be focused on our agenda, '" said this official, who requested anonymity to describe the private talks.
Mueller is supposed to carry on the investigation that former FBI director James Comey told Congress about before he was sacked by President Donald Trump. "I look forward to this matter concluding quickly". His firing of Former FBI Director James Comey last week intensified questions about whether he was trying to cover up collusion between his campaign and Russian Federation.
The focus now turns to how Mueller will pick up the FBI's investigation of the Trump campaign and Russian Federation, and what it means for the White House. But Mr. Mueller will not be subject to day-to-day oversight by Mr. Rosenstein or anyone else at justice. Since Sessions has recused himself from the Trump Russia investigation, Rosenstein - who signed the letter appointing Mueller as "acting attorney general" - is the only person with the authority to curtail Mueller's work.
With the White House running damage control, and critics smelling blood, some Democrats have mentioned the "I" word - impeachment - as a possibility for the 45th president, although initiating the procedure remains a hypothetical.
Meanwhile, Sen. Richard Burr of North Carolina said a lawyer for Flynn, a key figure in the Trump-Russia investigations, had told the intelligence committee that Flynn would not comply with the panel's subpoena for personal documents related to the committee's own probe. "He must ensure that this investigation is conducted without limits and without any political interference from the White House or Congressional Republicans".
"I just got a message from the president to stay strong", Flynn reportedly told the loyalists as he was finishing dinner. "His reaction was 'extremely measured, ' another said". Just a few months into his presidency, Trump has already amassed a collection of scandals and failures that most presidents take years to acquire. His appointment has been welcomed by politicians from both sides. Trump has long bristled at the notion that Russian Federation played any role in his November election victory.