So while the President's weekend attacks on the special counsel and his hiring of an aggressive ready-for-primetime lawyer Monday signaled a combative new phase in his defense, Trump was also taking some of the few practical steps at his command that do not risk grave political and legal consequences.

The flamboyant former US Attorney Joseph diGenova, who shares Trump's conspiratorial mindset, will certainly make his new boss feel better when he pops up on television, but he's unlikely to shift the fundamentals of the President's predicament.

What Trump would have to do to fire Mueller

What Trump would have to do to fire Mueller 01:01

What Trump would have to do to fire Mueller

That's because if Trump goes further than verbal assaults and tries to fire Mueller, he would usher in an epochal constitutional crisis. And his aggression in recent days shows he has rejected an alternative course of action: muting his natural inclination to go on the offensive while Mueller deliberates his fate.

So as the President slips political constraints by shuffling his White House and foreign policy team and rages against convention, Mueller and his investigators have Trump penned in with no easy means of escape. CNN reported on Monday that Mueller's team sat down with Trump's lawyers to discuss topics investigators could inquire of the President, a clear sign the investigation isn't likely to end anytime soon.

But cornered prey can be unpredictable and prone to desperate acts, so Trump's behavior is stoking concerns that he is not just hinting that he may can Mueller -- he may actually do it.

"We are fast approaching a crossroads ... where the United States is going to have to be confronted with a decision about whether we value the rule of law," Richard Ben-Veniste, a former Watergate special prosecutor, told CNN's Erin Burnett on Monday.

"This continued attack against Mueller, against the Department of Justice and against the FBI is a pretext for Mr Trump eventually to fire Mr. Mueller, I believe."

Trying to forcibly end the special counsel investigation would set up the ultimate test of the Republican Party's so far staunch unwillingness to desert its President, and could have a huge impact on the political environment for November's midterm elections.

Trump has repeatedly said there was "no collusion" between his campaign and Russia and no other wrongdoing. If that is the case, allowing Mueller to finish his investigation would provide vindication. But it's obvious that Trump sees the probe as so unfair and a conspiracy against him that is damaging his presidency -- a factor that may be inducing him to act as if he has something to hide, even if he doesn't.

And sitting powerless, while Mueller indicts people in his outer circle, pores over his financial records and looms ever closer to the Oval Office by the week is a scenario that is clearly driving Trump to distraction.

So it's reasonable to assume that diGenova's appointment represents Trump's frustration with his legal team and his limited options, following a weekend of conflicting statements from its members on the issue of Mueller's continued employment.

The technical business of lawyering -- evidenced Monday by a Washington Post report that the President's team is trying to limit the scope of any eventual interview with Mueller -- is also unlikely to give Trump a vent for his pent-up anger.

Lambasting a 'witch hunt'

The President's fury over his plight erupted in a series of attacks on Mueller over the weekend, culminating in an anguished tweet Monday lambasting an investigation he believes is part of an establishment plot to destroy him.

"A total WITCH HUNT with massive conflicts of interest!" Trump wrote, apparently testing out a rationale for the firing of Mueller, days after he singled out the special counsel by name in his attacks for the first time.

If that was a trial balloon for anything more than an effort to discredit Mueller's eventual findings, the President got a swift answer as several senior GOP senators warned that trying to rid himself of the Mueller probe would be disastrous.

Sen. John Cornyn of Texas said it would be a "bad idea" for Trump to sack Mueller, while Maine Sen. Susan Collins said such a step would be a "a terribly serious mistake."

GOP senators who don't have to face Trump voters anymore had more freedom. Utah's Orrin Hatch, for instance, said terminating Mueller would be "the stupidest thing" the President could do.

Still, after a weekend of assaults on Mueller by the President there was a noticeable lack of strong warnings by the two most important men in Congress, House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell

It's also clear that Republicans have little appetite for going on the record with a vote in Congress to introduce protections for Mueller in order to deter the President from trying to oust him.

The risks of firing Mueller

Toppling Mueller, with its constitutional implication of a President trying to evade accountability, would make the uproar following former FBI Director James Comey's firing last year pale by comparison. After all, jettisoning the former FBI director demonstrably made Trump's political and legal exposure over the Russia investigation much worse.

In fact, the only potential scenario in which Trump could benefit by firing Mueller would be if he does indeed have something to hide from the special counsel and he is able to permanently derail the investigation.

"Let's posit for a moment that there is something there ... in which case it is not the stupidest thing in the world to attack Mueller," David Priess, a former senior CIA officer and national security and intelligence author, told CNN's Brooke Baldwin on Monday.

"There may be something much worse out there, in which case this is not a stupid strategy at all. This would be protecting against the worst case scenario," Priess said.

Any attempt to dismiss Mueller would be complicated, however, and would require Trump to get rid of Attorney General Jeff Sessions -- who recused himself from involvement in 2016 election investigations -- and replace him with an interim successor who would consent to ordering the end of the investigation.

If the President is unwilling to go that far, the hiring of diGenova at least could settle his nerves and offer him an outspoken defender to bolster his under-gunned counterattack in the media.

JUST WATCHED Republicans warn Trump not to fire Mueller Replay More Videos ... MUST WATCH Republicans warn Trump not to fire Mueller 02:57

DiGenova is just the latest new entrant in Trump's circle who shares the President's combative mindset and is likely to take a far more aggressive public stance in defense of Trump than his current legal team has done.

Like new top economic adviser Larry Kudlow, diGenova is a talented performer on television. He's a regular on Fox News, the President's favorite source of political intelligence. Like Secretary of State nominee Mike Pompeo, he doesn't mince words and his appointment fits the President's emerging pattern of surrounding himself with subordinates who mirror his bravado and combativeness.

Showing his stomach for the fight, diGenova on Monday slammed what he said was disarray at the FBI under its director, Christopher Wray.

"What does that tell you about the FBI director? It tells you he is a coward," diGenova told WMAL radio.

DiGenova shares Trump's disdain for Comey, as well, once calling Comey his "own hagiographer" and a "danger to this country" on Fox.

DiGenova also has advanced conspiracy theories that the Russia investigation is an FBI plot to delegitimize Trump's presidency.