(CNN) Donald Trump and his political and legal teams are mounting an extraordinary escalation of his attacks against the special counsel's investigation, an apparent sign of increased worry among his allies that Robert Mueller's findings could potentially be deeply damaging to the President.

Trump issued his most explicit and public call on Jeff Sessions to shut down the probe on Wednesday, the latest of a series of threats and pressure on the attorney general and the Justice Department that if carried out would move the drama into Nixonian territory.

"This is a terrible situation and Attorney General Jeff Sessions should stop this Rigged Witch Hunt right now, before it continues to stain our country any further," Trump tweeted. "Bob Mueller is totally conflicted, and his 17 Angry Democrats that are doing his dirty work are a disgrace to USA!"

The flurry of activity comes a week after CNN reported that the President's former lawyer Michael Cohen is prepared to tell Mueller that the then-presidential candidate knew in advance about a Trump tower meeting in June 2016 in which Russians planned to offer dirt on Hillary Clinton.

Trump has denied all knowledge of the encounter.

And the tweets also coincide with the start of the trial of Paul Manafort that could boost the credibility of the special counsel operation if it secures a conviction and could also increase the chances that Trump's former campaign chairman decides to cooperate with Mueller.

Trump's words on Sessions set his lawyers and subordinates scrambling and could become a legal liability as the special counsel seeks to establish whether there was a corrupt motive in any effort by the President to obstruct justice.

It also followed a week in which several Trump legal representatives, including Rudy Giuliani, began to publicly question whether collusion -- the question of whether Trump or aides conspired with Russia on election meddling -- is actually a crime.

Those musings set off a torrent of speculation over whether Giuliani understands there is evidence to support such a finding by Mueller and whether he was therefore trying to defuse its potential impact.

Then, on Wednesday, Giuliani again upped the stakes, warning that the coming midterm election would be fought on the question of whether Trump would be impeached.

His comment was clearly part of an effort by Trump's team to motivate the President's supporters to go the polls in the midterm election to stave off a blue wave that could help Democrats seize the House of Representatives.

But it also implied that Mueller could produce evidence in a report that Deputy Attorney General Rod Rosenstein will feel compelled to send to Congress for possible impeachment proceedings.

A Republican House is seen as far less likely to move against the President, especially after the President's intense efforts to persuade his supporters that the Mueller investigation is corrupt, unfair and biased against him. It could be a much different story under a new Democratic House if the midterms go against the GOP.

Since no one outside Mueller's inner circle knows the extent of the evidence he has collected, and few people not in Trump's orbit have a full picture of his potential exposure, it is impossible to say for sure what is motivating the apparent evolution in the President's defense.

But it does appear that significant statements from the President this week and his legal and political teams at least embrace the possibility that their defense must eventually need to move on from the theoretical possibility of an adverse report by Mueller to a practical response to such an eventuality.

Could a tweet be evidence of obstruction?

Trump's tweet to Sessions immediately provoked conversation about whether he had shown an intent to obstruct justice in plain sight, following a long succession of previous tweets pressuring Sessions that appear to undermine arguments that Trump was acting with no malice in firing former FBI Director James Comey at the time he was in charge of the Russia investigation.

"This is another piece in the puzzle to someone trying to put together a picture of attempted obstruction," said Preet Bharara, the former US attorney for the Southern District of New York on CNN's "The Situation Room."

"Over time, a portrait is developing that the President wants the Russia investigation to be ended."

But Giuliani and the White House argued that the President was merely exercising his right to free speech and offering an "opinion." The former New York mayor pointed out that Trump said Sessions "should" stop the probe not that he "must" stop the probe.

White House press secretary Sarah Sanders, while lashing the "corruption" and "dishonesty" of the "witch hunt," said, "It's not an order, it's the President's opinion." In defense of the President, other Republicans pointed out that Sessions did not have the capacity to end the investigation anyway, since he has recused himself in favor of Rosenstein.

The pushback from the Trump camp revived the debate over whether Trump's tweets are official statements of policy and intent, or should merely be taken as some kind of ongoing conversation with the American people that has no political or legal significance.

From Mueller's point of view, it may not matter. The New York Times reported last week that Mueller was examining Trump's tweets about Sessions and Comey as he considers whether Trump showed corrupt intent in the firing of the former FBI director and puts pressure on the attorney general in a way that suggests a pattern of obstruction.

"Your motivation, the reason why you do something, your opinion actually has legal significance here," said Susan Hennessey, a CNN legal and national security analyst. "We know that Robert Mueller is looking at these tweets for exactly this purpose."

The tweet could also take on more significance should Trump decide in future to dismiss Sessions in order to appoint an attorney general who is not recused from oversight of the Mueller investigation who would be prepared to shut it down.

But Giuliani this week ridiculed the notion of "obstruction by tweet."

Trump in a dark place

It is not clear exactly what brought on Trump's latest volcanic intervention in the Mueller drama. But he is clearly agitated abou t the meltdown of his relationship with Cohen, amid rising speculation that his one-time confidant could agree to a plea deal if he is charged as a result of a federal probe in New York and could spill secrets to prosecutors about Trump's financial affairs.

Though the White House insists that the Manafort trial in Virginia on tax and fraud charges has nothing to do with the President -- Trump's tweets appear to indicate that he is closely keeping tabs on news coverage of the case

"Looking back on history, who was treated worse, Alfonse Capone, legendary mob boss, killer and 'Public Enemy Number One,' or Paul Manafort, political operative & Reagan/Dole darling, now serving solitary confinement - although convicted of nothing? Where is the Russian Collusion?" Trump tweeted.

CNN's Kevin Liptak reported Wednesday said that there was not one trigger for the President's Twitter rage on Wednesday but that he's been angry for months about Sessions and was sent into a dark place by the stories about Cohen last week.

Trump also lamented "a lot of bad people in Washington" on Wednesday, during a call with Rush Limbaugh's radio show, though it wasn't clear to whom he was referring.

"You have a lot of bad people in Washington. You knew that a long time ago, frankly, before I knew it," Trump said, congratulating Limbaugh on his 30th anniversary of his radio program. "I had no idea how evil some of them are, but you have a lot of great people too. And outside of Washington you have the greatest people in the world."

But his behavior is perplexing allies who believe that the President would be best served by not behaving in a way that makes it look as though he has something to hide and expects Mueller's investigation to be ultimately damaging towards him.

Republicans who are eying tough midterm elections in November just wish the President would keep his attention on what they believe is a credible story they have to tell on the economy.

"The President can voice his opinion, I don't deny him that ability, in this case I wish he wouldn't I just don't think it helps him," Republican Rep. Chris Stewart of Utah told CNN's Wolf Blitzer.

He added, "I wish he would just let the special counsel finish his work and show the American people what he has found."

This story has been updated with additional Trump tweets and statements.