Washington (CNN) The sound of silence is driving Washington to distraction.

The clearest signs yet that the monastic special counsel Robert Mueller may be about to file his final report with Attorney General William Barr have sent Beltway insiders to a state of nervous alert.

But there is no report yet.

So White House lawyers, Trump campaign flacks, key congressional offices and newsrooms are left counting the hours, poised to shape the end game of the most important investigation into a President's behavior in at least 20 years.

For everyone involved, it's like waiting for a jury in a big trial to reach its verdict: long stretches of edgy idleness are laced with the prospect of frenetic action and hugely consequential outcomes that could unfold at a moment's notice.

This moment of political purgatory comes after a turbulent two years packed with revelations about covert contacts between associates of President Donald Trump and Russia, the sight of Trump acolytes being sent to jail after sensational court dramas and a ferocious campaign by the President to discredit Mueller.

When he finally files his report, the special counsel will open a new chapter in the Russia story -- even though it could take weeks for most Americans to learn what he learned during his investigation.

Depending on his conclusions, he could either lift the cloud of suspicion over alleged links to Russia that has darkened every day of the Trump administration.

Or if he finds serious wrongdoing, Mueller could trigger a constitutional showdown that puts a presidency in peril.

Trump, in an interview with Fox Business Network that was released Friday morning, spoke ominously about the aftermath of Mueller's report, saying "people will not stand for it" if the report casts him in a bad light.

Rising tensions

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Just after sunrise Thursday, Mueller was met by camera flashes as he steered his car into the underground garage of the building where he has based his nearly two-year investigation into Russia's election meddling scheme.

A suddenly swelled media pack, huddling with their cameras under umbrellas in a chilly late March deluge, waited outside all day, vainly on guard for activity that could give some indication Mueller's time was up.

Tension simmered at the White House as the President's lawyers tested different scenarios that could ensue after Mueller files his report.

Like everyone else in Washington, Trump's team was in the dark, thanks to the leak-proof cone of silence that has enveloped Mueller, who has barely uttered a public word since he took his commission two years ago.

"We're tea leaf reading like everyone else," one White House official said.

Time hung heavy at the Justice Department. Reporters set up text chains to ensure that they didn't miss any breaking news on lunch or bathroom breaks.

ABC reporter Mike Levine wrote on Twitter that he encountered Barr in the building and got a "death stare" when he asked him, "Is today the day?"

In an information blackout, every anecdote is a potential clue.

When Mueller's soon to depart right hand man Andrew Weissmann sported a tan suit Wednesday, reporters and legal insiders wondered whether his ensemble hinted at an end of term mood in the special counsel's office.

The starchy Mueller, a former FBI director and decorated Marine, is famous for selecting a crisp white shirt, sober suit and neutral tie every morning, and encouraging subordinates to do the same.

Signs of an imminent twist in the tale of the Russia story drew several key players back on stage.

Former FBI Director James Comey, whose firing by Trump led to Mueller's appointment, wrote in a New York Times op-ed that even though he thought the President was morally unfit to serve, he wasn't hoping for him to be exposed as a criminal.

"I'm not rooting for anything at all, except that the special counsel be permitted to finish his work, charge whatever cases warrant charging and report on his work," Comey wrote.

House Intelligence Committee Chairman Adam Schiff said in a pre-emptive shot in USA Today that any attempt by Barr to cover up Mueller's findings would "stain the (Justice Department's) reputation for years to come."

A fundraising committee affiliated with Trump's re-election campaign sought to fire up the President's base -- his best shield against a political death blow if the Mueller report contains damaging revelations.

"This Witch Hunt has been orchestrated by loser Democrats and their friends in the Fake News Media," the email read. "They claim they plan to release the report 'soon' but they've been saying that for OVER 2 YEARS."

Closure is a long way off

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Despite the explosion of anticipation, there is every chance that when, Mueller's report is finally filed, there will be a sense of anti-climax.

The first question will be a simple one.

"Is he in fact done?" said CNN legal analyst Michael Zeldin, a former colleague of Mueller.

"Is he telling the attorney general 'my investigation is over,' " Zeldin added.

It may be days, weeks or even months before most of America learns what is in the report.

According to Justice Department regulations, Mueller is required to file a confidential report with Barr. Then it will be up to Barr to decide how much of it can be disclosed to Congress and the public in his own report.

Barr said in his recent confirmation hearing that favored transparency but only within the scope of department rules and the law. That led some Democrats to warn the administration could try to suppress Mueller's findings.

"The attorney general, as I understand the rules, would report to Congress about the conclusion of the investigation," Barr said in his hearing.

"I believe there may be discretion there about what the attorney general can put in that report," he said.

Barr will also have to decide whether information in Mueller's assessment is likely to raise White House executive privilege assertions -- to protect consultations between the President and his closest advisers, or given that part of the probe is a counter-intelligence investigation should remain classified.

Trump on Wednesday muddied the waters on the question of transparency, telling reporters that he would be happy for the report to be released.

Yet his sincerity is questionable given a weekend tweet in which he appeared to advise Republicans in Congress to go ahead with the "game" around the report's disclosure.

Only Mueller knows how he will file

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Mystery also clouds the kind of report that Mueller will file.

One model would be for the special counsel to adopt a traditional, sparse prosecutorial approach to explain the cases he initiated and decisions he made not to charge other people linked to the case.

Still, a pared-down approach would ignore the significant public interest in his investigation -- given that it involved a question of whether an elected President conspired with a foreign power to win election.

Given the prevailing Justice Department opinion that a sitting President cannot be charged in a criminal case, it's possible that Mueller could put details of any incriminating conduct by Trump in his report.

If Barr felt compelled to pass the information onto Congress, it would be up to lawmakers to decide whether to institute the constitutional duty of impeachment proceedings to judge presidential wrongdoing.

The political storm

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As soon as Mueller files his report, the game of expectations setting and vying for political advantage will begin.

If Barr does not release something in short order, Democrats in Congress are likely to demand disclosure, armed with their subpoena power.

And Washington being Washington, leaks can't be ruled out.

Anything short of a finding that Trump aides openly colluded with Russia in 2016 and obstructed justice multiple times to cover it up -- for instance in the sacking of Comey -- is likely to be portrayed by the White House as a victory.

"This clears the decks for us," a Trump campaign adviser told CNN's Jim Acosta, reflecting a perceptible optimism in the President's camp in recent days that the report will not damage the commander in chief.

Though the President still faces multiple criminal and civil investigations into his inauguration, transition, and personal and business affairs, exoneration by Mueller would be hugely significant.

After repeatedly branding Mueller as an out of control prosecutor bent on a "witch hunt", Trump would seek to play up his sterling character. The Trump adviser even described the special counsel as a "boy scout" on Thursday.

But the President has also taken care to road test an argument he could use in the opposite scenario, arguing that Mueller should never have been appointed, and that the investigation itself represents a de-facto political coup.

"I had the greatest electoral victory -- one of them -- in the history of our country. Tremendous success. Tens of millions of voters. And now somebody's going to write a report who never got a vote," Trump said Wednesday.

Democrats are also gaming out how to respond to their report.

Critical findings by Mueller would immediately boost demands in the liberal grass roots for impeachment.

But if Trump escapes censure, Democrats must consider whether their own vast investigation into Trump's life and political career could come across to voters in 2020 as overkill, and offer an opening to the President.