President Trump's former campaign chairman Paul Manafort pleaded not guilty to a revised 5-count indictment in the Russia probe on Feb. 23, and is set for trial on Sept. 17. (Reuters)

A federal judge set a Sept. 17 trial date in Washington for former Trump campaign chairman Paul Manafort on Wednesday, setting up a potential test of special counsel Robert S. Mueller III’s Russia probe at the height of U.S. congressional election campaigns this fall.

U.S. District Judge Amy Berman Jackson scheduled the trial as Manafort appeared in federal court for the first time since co-defendant and longtime deputy Rick Gates pleaded guilty last week to reduced charges. Gates said he will cooperate in Mueller’s investigation of alleged Russian interference in the 2016 U.S. presidential election.

In October, Manafort, 68, and Gates, 45, both pleaded not guilty to the first charges leveled by the special counsel, a 12-count indictment accusing the men of conspiring to defraud the United States by hiding tens of millions of dollars since 2006 from their work for a Russia-friendly political party in Ukraine and former Ukrainian president Viktor Yanukovych.

In conjunction with Gates’s plea Friday, Mueller’s team added tax evasion and bank fraud charges against Manafort, who already faced counts of conspiracy to launder more than $30 million, making false statements, failing to follow lobbying disclosure laws and working as an unregistered foreign agent.

Who has been charged in Russia probe and why

Manafort pleaded not guilty Wednesday to a revised, five-count indictment in Washington. He is scheduled to enter a second plea Friday afternoon in federal court in Alexandria, where he faces 18 new and modified charges.

Manafort has a home in Virginia, and the counts of lying on tax returns and failing to report foreign bank accounts were filed there because of a technical requirement that the accused be charged in federal court in the state where he filed returns.

Jackson said Wednesday that Manafort and his defense team bear the greatest burden of potentially duplicative work if he faces a second trial with overlapping evidence in a neighboring jurisdiction. Prosecutor Greg Andres said he was not criticizing Manafort but noted that the defendant waived the option of a single trial.

Manafort attorney Kevin Downing indicated that he was prepared to fight both cases. A trial date has not been set in the Virginia case, although the Eastern District of Virginia is so well known for its rapid proceedings that it is nicknamed for its “rocket docket.

Jackson began the 30-minute hearing expressing condolences to Manafort for the loss of his father-in-law, who died Saturday. Manafort, who is under house arrest, thanked her for granting him permission to travel to Long Island to attend the wake and funeral and return home to Alexandria on Tuesday.

Jackson last week rejected Manafort’s bid to revise a previously approved $10 million bail deal by swapping out the properties he would use as security for bail. He said the judge inadvertently imposed conditions that in effect set a $17 million bail.

Prosecutors opposed Manafort’s request, alleging that he was involved in additional bank fraud conspiracies in which they contend Manafort inflated his income to get a $9.5 million loan secured by property he falsely said was mortgage-free.

Manafort asserted his innocence in a statement Thursday by his spokesman Jason Maloni.

“The new allegations against Mr. Manafort, once again, have nothing to do with Russia and 2016 election interference/collusion,” the statement said. “Mr. Manafort is confident that he will be acquitted and violations of his constitutional rights will be remedied.”

Jackson rebuked the defendant in court, saying she would take no action but that such comments violate a gag order in the case.

“I can certainly understand the impulse not to let that go by without asserting your innocence,” Jackson said. But she added that she believed the response to the prosecution was contrary to her order, which neither side opposed last year.

Downing said he would file a motion seeking to clarify that the order does not bar his defendant from exercising his constitutional rights.

Jackson noted that prosecutors want to use a written questionnaire to select jurors, but she warned both sides — who must agree on the form — that it must not be lengthy: not 200 questions, or 100, but “more like 50 questions or less, would be better.”

Also before Jackson is Manafort’s lawsuit challenging his indictment and Mueller’s appointment as special counsel, arguing that Deputy Attorney General Rod J. Rosenstein and Mueller have exceeded their authority in charging him. The Justice Department has asked Jackson to toss out the case, saying the proper forum for dismissing charges is his criminal case.