President Donald Trump's former campaign chairman Paul Manafort is set to ask a federal judge on Friday not to revoke his bail and send him to jail pending trial after Special Counsel Robert Mueller filed new charges of witness tampering last week.

Manafort, whose charges arise from Mueller's ongoing investigation into Russia's role in the 2016 U.S. presidential election, is expected to plead not guilty to the charges in the latest indictment against him during an arraignment before U.S. District Judge Amy Berman Jackson in Washington.

Manafort has been indicted by Mueller in both Washington and Virginia on a raft of charges including conspiracy against the United States. Jackson could immediately revoke his bail conditions and send Manafort to jail awaiting his trial scheduled for September in the Washington case.

His trial on the related charges in Virginia is set for July 25. Manafort has pleaded not guilty to all charges.

Manafort is currently confined to his home in the Washington suburb of Alexandria, Virginia, and forced to wear a GPS monitoring device.

Mueller, whose investigation could threaten Trump's presidency, is investigating whether the president's 2016 campaign colluded with Moscow and whether Trump has unlawfully sought to obstruct the Russia probe. Trump has called Mueller's investigation a witch hunt and has denied wrongdoing.

Jackson has rebuffed Manafort's repeated requests to end his home confinement in exchange for pledging $10 million in real estate as collateral.

A June 8 indictment charged Manafort and Konstantin Kilimnik, a Manafort aide and political operative with alleged ties to Russian intelligence, with tampering with witnesses about their past lobbying for Ukraine's former pro-Russian government.

The indictment accused Manafort and Kilimnik of attempting to call, text and send encrypted messages in February to two people from a political discussion group — the so-called Hapsburg Group — that Manafort worked with to promote Ukraine's interests in a bid to sway their testimony.

Mueller's team this month asked the judge to revoke Manafort's bail, saying his "obstructive" conduct "instills little confidence that restrictions short of detention will assure Manafort's compliance with the court's orders and prevent him from committing further crimes."

Manafort has longstanding ties to a pro-Russian political party in Ukraine and a Russian oligarch close to the Kremlin.

The charges against Manafort in Washington include conspiracy to launder money, conspiracy to defraud the United States and failing to register as a foreign agent for the pro-Russia Ukrainian government under former President Viktor Yanukovych.