Paul Manafort's financial crimes trial, the first arising from special counsel Robert Mueller's investigation, will center on his Ukrainian consulting work and only briefly touch on his involvement with the president's campaign.
Manafort was initially ordered to remain under house arrest as he awaited trial, but U.S. District Court Judge Amy Berman Jackson, who is presiding over the case in the District of Columbia, sent him to jail in June after prosecutors flagged evidence that Manafort had been trying to influence the testimony of potential witnesses.
Paul Manafort on Tuesday will become the first of President Donald Trump's former aides to go on trial, accused of bank and tax fraud by federal investigators probing Russian meddling in the 2016 USA presidential election.
Mueller's team has estimated it could take eight to 10 days to present its case to the jury, suggesting the trial may last at least three weeks.
But Mr Manafort quickly faced allegations that he had not disclosed millions of dollars he received for consultancy work he carried out in Ukraine for its then pro-Russian president.
Mueller is now investigating Trump’s tweets
Mueller is also interested in Trump's attacks on Comey, which include a veiled threat about taped conversations between the two men.
In the Virginia trial, which begins Tuesday, Manafort faces charges of filing false tax returns; failing to report foreign financial accounts; and bank fraud and conspiracy.
As president, Trump has downplayed Manafort's role in the campaign.
"You don't really care about Mr Manafort's bank fraud", Judge TS Ellis said.
On Monday, prosecutors said in court filings that they meant to prove Manafort earned more than $60 million lobbying for the former pro-Russia Ukrainian government and failed to report "a significant percentage" of that. Gates pleaded guilty in February and has been cooperating in the Mueller probe. He has also put distance between himself and Mr Manafort's charges, saying in a tweet: "This is years ago, before Paul Manafort was part of the Trump campaign". The charges stem from Manafort's activities from 2006-2017.
Rudy Giuliani, a lawyer for Trump, said no one facing trial should expect a pardon, but he did not rule one out. Gates, who worked alongside Manafort as a political consultant, was indicted along with Manafort in October 2017.