The President also suggested that the investigation that will now be led by former FBI Director Robert Mueller was also motivated by an attempt to tarnish his election victory last year.

"It also happens to be a pure excuse for the Democrats having lost an election that they should have easily won because of the Electoral College being slanted so much in their way. That's all this is. I think it shows division, and it shows that we're not together as a country. And I think it's a very, very negative thing. And hopefully, this can go quickly, because we have to show unity if we're going to do great things with respect to the rest of the world."

Trump's push back contrasted sharply with the near universal welcome in Washington for Mueller, the former FBI director picked for the special counsel post Wednesday by Deputy Attorney General Rod Rosenstein.

Sen. Lindsey Graham, leaving the senators' briefing with Rosenstein, said Thursday he believes the Russia investigation is "now considered a criminal investigation."

"Congress' ability to conduct investigations of all things Russia has been severely limited, probably in an appropriate fashion," the South Carolina Republican said, as a result of Mueller's appointment. He added he wasn't able to ask specifically if it was now a criminal probe "but the takeaway I have is, everything he said was that you need to treat this investigation as if it may a criminal investigation."

With all of the illegal acts that took place in the Clinton campaign & Obama Administration, there was never a special councel appointed! — Donald J. Trump (@realDonaldTrump) May 18, 2017

This is the single greatest witch hunt of a politician in American history! — Donald J. Trump (@realDonaldTrump) May 18, 2017

In a series of early morning tweets, Trump complained that he was being singled out in a way Democrats had not been.

"With all of the illegal acts that took place in the Clinton campaign & Obama Administration, there was never a special (counsel) appointed," Trump tweeted. "This is the single greatest witch hunt of a politician in American history."

The President's tweets appear to signal a policy of resistance to Mueller's investigation, that will now likely cast a shadow over the beleaguered White House for months if not years to come. His attacks may also represent an attempt to rally his fiercely loyal political base which embraced him precisely because he was an outsider willing to challenged the established centers of power in Washington.

The naming of Mueller represents a threat to the White House because he will be armed with sweeping powers, including the right to subpoena documents or interview the President as he builds a case centered on the question of whether anyone in Trump's circle colluded with the Russians to influence the course of the election or committed any crimes.

The President's adoption of the role of a victim has been a potent political weapon before and he has frequently used it to position himself against the Washington establishment, including the media which he uses as a foil in the absence of an easily identifiable political enemy, like Hillary Clinton.

JUST WATCHED Trump calls Russia probe 'greatest witch hunt' Replay More Videos ... MUST WATCH Trump calls Russia probe 'greatest witch hunt' 02:11

Departure from White House stance

Trump also has a habit of seeing political events through a prism of his own image and how they affect his reputation. In this case, painting himself as the unfair target of an investigation that was widely applauded across the political spectrum may instead serve to highlight his isolation. It may also be seen as an attempt to discredit the inquiry before it starts or to prejudge its results.

The President's comment may also conflict with a sound legal strategy, given that he could eventually be called upon to testify to Mueller's probe.

The tweets fly in the face of the statement issued on Wednesday night which had appeared as an attempt by Trump's staff to tamp down the raging political storm over Russia which has resulted in Trump's worst week in office so far.

Trump said in a restrained statement Wednesday that Mueller's "thorough investigation will confirm what we already know -- there was no collusion between my campaign and any foreign entity," adding that he looked forward to a speedy resolution to the probe.

Once again, Trump's tweets on Thursday saw him stake out a radical departure from the official White House line on an important issue, a habit that has repeatedly undermined his press operation in recent days, and made it even more difficult for his administration to move on from a string of self-imposed crises.

The same pattern was in evidence when he fired FBI Director James Comey last week then used a television interview to suggest he acted out of frustration with the FBI's Russia probe -- even though his team spent several days saying the ousting of the bureau's director had nothing to do with that issue.

Comey's dismissal and Trump's remarks appear to have helped sway Rosenstein's mind as he contemplated appointing a special counsel.

The announcement of a special counsel on Wednesday came with Trump already fuming about his treatment in Washington and about what he sees as the rank unfairness of claims that Russian hacking operations helped elect him last November.

"No politician in history, and I say this with great surety, has been treated worse or more unfairly," Trump said in a commencement address at the United States Coast Guard Academy on Wednesday.