Gates, Manafort's longtime business partner and Trump's deputy campaign chairman, was working on the transition team and the inauguration.
"After all the lies you've told and fraud you've committed, you expect this jury to believe you?" U.S. District court Judge T.S. Ellis III presides.
As part of his plea agreement to cooperate with prosecutors, Gates also admitted to lying to investigators from the special counsel's office - a fact Downing also seized upon. Downing pressed him on the specifics of their business relationship: which payments to Gates were authorised and which were not. Trump often boasts that he hires "the best people", and the sixth day of the trial showcased two people who worked for him, one who allegedly tried to use his influence in Trump's circle to boost someone he had a sketchy financial relationship with, and another who admitted under oath that he may have stolen money from Trump's inaugural committee.
Gates acknowledged that he did for two months and that he took first-class flights and stayed in "fancy hotels" around Europe, but said the money came from bonuses rather than illicit gains.
Gates, who is awaiting sentencing, told jurors that he siphoned off money without Manafort's knowledge by filing false expense reports.
Defense lawyers wrapped up their questioning of Gates Wednesday following a bruising cross-examination that focused on Gates's own crimes, an extramarital affair and a guilty plea with special counsel Robert Mueller's office that may spare him severe punishment.
The 46-year-old former political consultant told jurors how Manafort asked for tickets to Trump's inauguration so he could give them to a banker involved in approving a loan at the center of his financial fraud trial. Gates said he was responsible for collecting all relevant documents for the loan applications.
In one example, Manafort and Gates emailed each other copies of a doctored profit and loss statement they later sent a bank to help Manafort obtain a loan.
The tough questioning of Gates came after he spent hours telling jurors how he disguised millions of dollars in foreign income as loans in order to lower Manafort's tax bill.
Once-eased USA economic sanctions against Iran back in effect
We would like to see a change in the regime behavior, and I think the Iranian people are looking for the same thing". Hassan Rouhani , the Iranian president, hit back by calling the move " psychological warfare ".
"The idea of exchanging income for loans reduced his overall tax liability", Gates said.
Rick Gates, the former business partner of Paul Manafort, testified Tuesday that he helped Manafort hide payments from offshore accounts. But Trump has shown interest in the proceedings, tweeting support for Manafort and suggesting he has been treated worse than gangster Al Capone.
During questioning by prosecutors on Tuesday morning, Gates said that Manafort had emailed him in late 2016 asking for the incoming Trump administration to consider tapping Federal Savings Bank Chief Executive Steve Calk for Secretary of the Army.
Kevin Downing, right, attorney for Paul Manafort, leaves federal court after attending the trial on tax evasion and bank fraud of the former Donald Trump campaign chairman in Alexandria, Va., on Tuesday. He also committed credit card and mortgage fraud, falsified a letter for a colleague involved in an investment deal and made false statements in a deposition at Manafort's direction.
Gates said it was a "very common method" for Dr. K and that, once the money was moved into the accounts, Manafort decided what to do with it.
For this Manafort was paid US$4million a year, in quarterly payments of US$1million, Gates recalled, though at some point the currency switched from United States dollars to Euros.
Prosecutors had intentionally left many of these pieces of evidence blank on an itemized list of documents they are presenting in court, signaling they could be the most sensational and attention-grabbing files in the evidence binder. Manafort broke his stare only to review government exhibits on a small monitor in front of him.