(Reuters) - The criminal trial of President Donald Trump’s former campaign chairman Paul Manafort was delayed on Monday by one week, with a U.S. judge making public the names of five witnesses granted immunity to testify.

Manafort’s trial on 18 charges, including bank and tax fraud and failure to file reports of foreign bank and financial accounts, will now begin on July 31. The longtime Republican operative and businessman has pleaded not guilty to the charges.

It will be the first trial to originate in the special counsel’s investigation of Russia’s role in the 2016 U.S. election.

Following is a summary of some of the individuals set to play key roles in the case:

Paul Manafort was Trump’s campaign chairman from May 19 to Aug. 19, 2016. His bail was revoked on June 15, and he remains jailed ahead of his trial. He faces a separate trial in September for related charges, including witness tampering.

Robert Mueller is the U.S. special counsel for the investigation of Russian interference in the 2016 election, possible obstruction of justice and alleged financial crimes by Manafort and others. He was appointed on May 17, 2017, by Deputy Attorney General Rod Rosenstein.

Richard Gates is a former deputy campaign chairman for Trump who has agreed to cooperate with the Mueller probe. He pleaded guilty in February to conspiring against the United States and lying to investigators.

George Papadopoulos is a former Trump campaign adviser who pleaded guilty last autumn to making false statements to the FBI about his contacts with Russia. He has been cooperating with Mueller. According to documents released with his guilty plea, Papadopoulos offered to set up a meeting between Russian President Vladimir Putin and then-candidate Trump.

Corey Lewandowski had been Trump’s campaign manager before Manafort took over in May 2016. He was fired from the campaign a month later. Lewandowski has been interviewed several times by the House of Representatives Intelligence Committee, which is also investigating possible meddling by Russia in the election. Committee members said Lewandowski refused to answer many of their questions.

Carter Page, also a former Trump campaign adviser, was under surveillance by the FBI as part of a probe into whether he conspired with the Russian government to undermine the 2016 election. Documents released on Saturday related to the surveillance said that Page “has established relationships with Russian Government officials, including Russian intelligence officers.”

Michael Flynn, former White House national security adviser and campaign aide, pleaded guilty in December to lying to FBI agents about his conversations with Russia’s then-ambassador, Sergei Kislyak, and agreed to cooperate with Mueller’s investigation. He was the first member of Trump’s administration to plead guilty to a crime uncovered by Mueller.

U.S. District Judge T.S. Ellis III is presiding over Manafort’s case and has questioned the scope of Mueller’s probe. He said that Manafort’s indictment seemed aimed at getting him to provide information on Trump. Ellis, appointed by former President Ronald Reagan in 1987, is based in Alexandria, Virginia.

Alex Van der Zwaan is a Dutch lawyer who previously worked with Manafort and Gates. He was sentenced in April to 30 days in prison for lying to Mueller’s investigators. He was the first person to be sentenced in Mueller’s probe.

Jeffrey Yohai is Manafort’s former son-in-law and business partner. He reached a plea deal with Mueller’s office in May requiring him to cooperate with other probes.

Bruce Baldinger is a longtime real estate lawyer for Manafort. He signed biennial statements as the authorized person for two of Manafort’s New York companies, which prosecutors allege were part of a scheme to take tens of millions of dollars earned overseas and launder it in the United States. In June, Baldinger retained an ethics attorney as a legal consultant.

Rick Davis, one of Manafort’s business partners, arranged in 2008 for then-Republican presidential candidate John McCain to meet with Oleg Deripaska, a Russian billionaire. He served as McCain’s presidential campaign manager in 2000 and 2008.

Tony Podesta, a prominent Washington lobbyist, stepped down from his firm in October as investigators examined his company’s ties to Manafort. The firm, Podesta Group, lobbied on the behalf of the European Centre for a Modern Ukraine, which was named in the Manafort indictment.

Potential government witnesses whose identities were made public on Monday by Ellis:

Dennis Raico was an executive at Federal Savings Bank, a Chicago-based lender that extended Manafort $16 million in loans against his New York real estate. Mueller has said he would introduce evidence at trial showing a connection between the loans and an effort by Manafort to get the bank’s CEO positions on Trump’s campaign and in the administration. Federal’s chief executive is Steven Calk, who had an advisory role in the Trump campaign.

James Brennan is also an executive at Federal Savings Bank.

Donna Duggan is an insurance agent at Moody Insurance Worldwide, based in Germantown, Maryland. She worked on insurance related to a Brooklyn, New York, townhouse against which Manafort borrowed money from Federal Savings Bank, according to an email listed as potential evidence in Manafort’s trial in a court filing submitted by Mueller.

Cindy Laporta is an accountant at the Virginia-based accounting firm KWC. The firm said it prepared individual and business tax returns for Manafort.

Conor O’Brien was formerly employed at KWC.