The charges cover a period that includes political work the Republican Party lobbyist and consultant did in Ukraine years before he joined Trump’s campaign but also extend to more recent loan applications while he was staffing the future president. Experts call the stakes high all the same.

“The din of the verdict will be deafening,” said Mark Corallo, a former spokesman for both Trump’s legal team and the George W. Bush Justice Department.

“If Manafort is acquitted it’ll be the pro-Trump side blasting the special counsel, blasting the whole process, urging for the dismissal of the office of special counsel and shutting down the investigation and all of that.”

“If it goes the other way,” he added, “the left and anti-Trump side will be screaming at top of their lungs that Trump should be impeached.”

Don Goldberg, a former Clinton White House crisis communications spokesman, said the outcome could have practical legal implications for Mueller as well as political ones.

“It’s important for his whole legal strategy,” Goldberg said.

“If he can’t get a conviction, not only does it undermine the credibility of the entire investigation, but it also sends a signal to other targets that the cases against them are even less likely to succeed.”

That could encourage other Mueller targets to dig in deeper and resist offers to trade immunity for cooperation.

A not-guilty verdict could also undermine Mueller’s seemingly tenuous Republican Party support on Capitol Hill, Goldberg said, emboldening Republicans to soften their opposition to Trump interfering in the probe.

On the flip side, a guilty verdict could allow Mueller to press Manafort to incriminate other Trump associates in return for a lenient sentence – although there is no guarantee the presiding judge would grant leniency.

The special counsel has also indicted more than 30 other people and companies – most of them Russian – while also netting guilty pleas from former Trump national security adviser Michael Flynn and former Trump campaign aide George Papadopoulos.

While the courtroom proceedings is likely to touch on Trump and his 2016 campaign, legal analysts don’t expect major revelations about Russian election meddling and contacts between Trump and his associates and Kremlin-linked Russians.

Mueller is not expected to appear in the ninth-floor Alexandria courtroom. But his presence will be felt all the same.

Several members of his team filled seats around the prosecution’s table during last week’s preliminary court hearings, while Mueller’s top spokesman, Peter Carr, sat inconspicuously in seats open to the general public.

Real-time coverage of the trial will be limited. Courthouse rules prohibit cameras or electronic devices like laptops and iPhones, meaning reporters cannot even live-tweet proceedings from within the courtroom.

Manafort is expected to face a second trial starting September 17 in a Washington DC federal court, on charges of money laundering and failing to register as a foreign agent in connection with his Ukraine-related lobbying work.

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Alan Dershowitz, a retired Harvard law professor and frequent Trump defender, said he is sceptical that a jury will clear Manafort.

“They’ll only bring the case if it’s a slam dunk,” he said of Mueller’s team.

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But he also predicted the special counsel would suffer if his team did fall short in court. “Anything other than a conviction would be something the president could take a victory lap on and something that’d hurt Mueller’s credibility,” he said.

Not everyone agrees that the trial is a must-win for Mueller, however.

“Mueller has already indicted over 30 people and every new piece of evidence that’s come out has reinforced the need for this investigation,” said Robby Mook, Hillary Clinton’s 2016 presidential campaign manager.

“The real question is what new evidence we learn from this trial, either through what’s presented by the prosecution or if Manafort eventually makes a plea deal.”

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Mike Quigley, a Democratic member of the House Intelligence Committee, said that, regardless of the trial’s outcome, the proceedings will be an important window into money-laundering practices – an issue many Democrats charge Trump may have engaged in himself, but which the Republican-led Congress has largely sidestepped.

The Illinois congressman and former defence lawyer added that a guilty verdict would be a powerful rebuttal to Trump’s favourite talking point about the Russia probe.

“It throws additional water on his fire of ‘hoax’ and ‘witch hunt’," he said.

Still, Quigley said is wary of assigning the outcome with too much meaning.

“Trials are trials. Juries are juries,” he said.

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“You never know how they're going to act.”

Giuliani told POLITICO that the president’s legal team will keep its distance from the Manafort trial and won’t send anyone to watch from inside the courtroom.

The former New York mayor also said he wouldn’t be surprised to see Trump celebrate a Manafort acquittal, adding that a Manafort conviction would likely leave Mueller’s team feeling “more emboldened.”

But Giuliani also downplayed the import of it all.

“Both are just obvious ways in which people will play it,” he added.

“Probably, both are an overreaction.”

Kyle Cheney contributed to this report