(CNN) Almost all he had left was Hope.

President Donald Trump was left more beleaguered and isolated than ever after the resignation of his confidante Hope Hicks, one in the core of "originals" who had nurtured the iconoclastic tycoon all the way to the White House.

Hicks dropped her shocking announcement on a day that was bewildering even by the extreme standards of this White House, leaving Trump's presidency looking increasingly unmoored.

The departure of Hicks -- the young woman who became as much an emotional crutch as a communications director -- leaves the inner circle of a President for whom loyalty is an obsession in tatters.

"As a CEO, or as a President or anyone at the top, it is lonely, and when you go in there you have the team, and you have your team," Rob Astorino, a longtime friend of the President's, told CNN's Erin Burnett on Wednesday. "Your team are the people that know you best and you really, really trust."

"Hope was one of the people he really, really trusted," Astorino said. "So with her leaving, there is only a handful left, and he's going to feel like he is on an island."

Hicks' departure will come at a moment of maximum instability for the White House, with staff morale plummeting and the prowling presence of special counsel Robert Mueller and his Russia probe becoming ever more oppressive.

Trump's White House has been a whizzing revolving door for aides, officials and cabinet members whose stars often burn bright, then quickly burn out. Outsize personalities like Steve Bannon, fixers like first chief of staff Reince Priebus and retainers like Sean Spicer are all long gone.

But Hicks is one of the first among equals whose loyalty to Trump is unquestioned, and her exit will particularly sting, several aides told CNN. Not many people are irreplaceable. But for Trump, Hicks probably is.

"I don't think it's possible to overstate the significance and just the importance of her role within the White House. She's an invaluable team member and one of the originals," one Trump ally told CNN's Jeremy Diamond.

The loss of Hicks comes with other pillars of the President's Oval Office support network already felled or wobbling badly.

The political careers of Jared Kushner and Ivanka Trump are teetering, with the President's son-in-law's lost top-secret security clearance threatening his role as Trump's foreign policy consigliere.

Earlier soul mates like former campaign chief Corey Lewandowski never made it to the White House. Keith Schiller, Trump's former bodyguard, left last year. National security adviser Mike Flynn was gone in disgrace after a couple of weeks. And Trump's billionaire pal Tom Barrack didn't sign up for political service, nor did the President's ultra-loyal gatekeeper of many years Rhona Graff.

One loyalist who is still around is social media specialist Dan Scavino.

All of Trump's departed inner circle friends will still be available to him on the outside, for the President's daily roster of calls to vent and solicit advice.

But it's looking possible that soon, none will be by his side, and that means life in the Oval Office could get very lonely indeed for the President.

Months ahead might be tough for Trump

All presidents experience the loneliness of office, the pressure of the responsibilities they bear and the slings and arrows of life in the political jungle of Washington.

But given Trump's gregarious personality, limited attention span and status as an outsider in the corridors of power, the months ahead could be especially tough.

That means unconditional loyalty is especially important.

Another former White House communications director, Jen Psaki, who served in the Obama administration, said that when people such as Hicks depart the West Wing they leave an emotional void, for other staffers as well as the President, describing Hicks as the "tamer of the savage beast" that is Trump.

That could mean more time home alone for Trump. More bouts of self-destructive tweeting, unpredictable behavior and lashing out from a President who lacks a Washington network, gravitates to safe spaces at his resorts every weekend he can and often seems to spend hours live tweeting Fox News.

Despite her loyalty to the President, in time Hicks may end up as one of the people drawn into his presence whose reputations never quite recover.

There is intense speculation as to why she decided to jump on Wednesday, 24 hours after a day of testimony to a House panel investigating alleged collusion between the 2016 Trump campaign and Russia.

Or perhaps she was pushed?

CNN's Burnett reported that Trump had berated Hicks on Tuesday after she admitted in the grueling hearing that she had sometimes had to tell "white lies" for her boss. The White House denied the report.

Some experts believe that her role in the drafting of an inaccurate statement -- about a meeting between Donald Trump Jr. and Russian interlocutors during the campaign -- aboard Air Force One last year could have taken her into personal legal jeopardy.

She was also recently involved in handling the scandal over former White House aide Rob Porter, with whom she was in a relationship at the time, and who was accused of physical abuse by two ex-wives.

And her proximity to the President means she is bound to be of intense interest to Mueller's team of high powered prosecutors, a reality that is certainly forcing her to endure significant strain.

Hicks tearfully told White House communications staff Wednesday that the time was simply right for her to go, CNN's Kaitlan Collins reported.

It's hard for anyone who has not worked in the White House to appreciate the grueling hours, exhaustion and pressure that come with life in the West Wing, feelings of burnout Hicks must surely be feeling.

But given her nine hours of testimony Tuesday, position at the center of an intensifying special counsel dragnet and other recent events, her explanation that other opportunities were beckoning is tough to swallow.

A sense of disequilibrium

The Hicks news Wednesday was just the latest in a succession of broadsides to hit the scandal-plagued White House in the last 48 hours that suggest Mueller's probe is getting ever closer to the President.

The Washington Post reported Wednesday that the special counsel was now investigating the President's apparent effort to oust Attorney General Jeff Sessions, who recused himself from the probe, last summer.

On Tuesday, CNN revealed that Mueller was also looking at Trump's business transactions in Russia prior to his presidential campaign.

Both approaches could be related to any attempt by the special counsel to decipher whether the President obstructed justice in the firing of former FBI Chief James Comey, in order to cover up any compromising links with Russia.

Those bombshells came on the heels of news Tuesday that Kushner had his top secret clearances stripped by chief of staff John Kelly. A Post report on the same day said several foreign nations had discussed how his family's heavy debt load and his own inexperience could be used to manipulate Kushner in his role as Trump's foreign policy guru.

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The sense of disequilibrium surrounding the White House was exacerbated by Trump's latest attack on Sessions on Wednesday, over the attorney general's handling of an investigation into alleged surveillance abuses. Trump called Sessions' conduct "disgraceful."

And the sense of a presidency at sea was further reinforced by an extraordinary session in the White House compered by the President in which he seemed to completely repudiate core Republican positions on gun control.

At one point he seemed to agree to include a ban on assault weapons in "comprehensive" gun control legislation, a comment that prompted the idea's sponsor, Democratic Sen. Dianne Feinstein of California, to rub her hands with glee.

Trump's comment that maybe authorities should "take the firearms first and then go to court" if someone suspected mental illness repudiated conservative dogma.

The candidate who ran for office warning that Democrats wanted to end the Second Amendment appeared to have adopted the positions of his predecessor Barack Obama wholesale.

"Trump the gun grabber" was the headline on Breitbart News, encapsulating the surreal nature of yet another logic busting day in Washington.