A federal judge has postponed from Wednesday until July 31 the start of the upcoming trial of President Donald Trump's former campaign chief Paul Manafort after Manafort's lawyers complained of having a vast amount of newly disclosed documents to sift through.

Judge T.S. Ellis III also granted immunity to five potential witnesses for their testimony at that trial in U.S. District Court in Alexandria, Va.

The potential witnesses were identified as Dennis Raico, Cindy Laporta, Conor O'Brien, Donna Duggan and James Brennan. All five people appear to work at various financial institutions that have been linked to Manafort either in court filings or published reports.

The determination of whether to call the witnesses to testify will be made by prosecutors during the trial.

Prosecutors in the office of special counsel Robert Mueller had asked for so-called use immunity for the five witnesses, which would bar their testimony at Manafort's trial from being used against them in a criminal prosecution. Ellis' decision to grant them use immunity does not preclude the quintet from being charged on the basis of other evidence.

Without immunity, Mueller's office had said, the witnesses would have refused to testify by invoking their Fifth Amendment rights against self-incrimination.

Raico is an employee of Federal Savings Bank, a Chicago-based institution. NBC News reported in February that federal investigators were probing whether Manafort had promised Stephen Calk, the president of Federal Savings Bank, a job in the Trump White House in exchange for $16 million in homes loans.

Neither Raico nor any of the other four people granted use immunity by Ellis on Monday have been charged with a crime.

Ellis, during a hearing Monday, heard arguments from Manafort's defense team on their request for the delay.

Manafort's lawyers have argued that a postponement is warranted due to the need to sift through the voluminous amount of documents recently turned over by prosecutors to the defense team.

Manafort also faces a separate criminal case in Washington, D.C., federal court where a trial on related charges currently is scheduled to begin in September.

Both cases relate to consulting and lobbying work Manafort did on behalf of pro-Russian politicians in Ukraine.

Manafort had been confined to his home on a $10 million release bond until June, when prosecutors accused him of trying to tamper with potential witnesses against him. He has since been in jail.