Steve Bannon, the former White House chief strategist, will be a star witness at the trial in Washington of Roger Stone, a longtime political operative and ally of Donald Trump, a court heard on Wednesday.

The surprise announcement was made during opening statements on Wednesday by prosecutor Aaron Zelinsky, who told the court that Stone had “straight-up lied” to the US Congress about aspects of the 2016 election campaign “because the truth looked bad for Donald Trump”.

A self-described “dirty trickster”, Stone is accused of lying to the House of Representatives intelligence committee about the Trump campaign’s efforts to obtain emails hacked by Russia that were published by the WikiLeaks website with the effect of harming Trump’s Democratic rival Hillary Clinton.

On day two of Stone’s trial at a federal court in Washington, Zelinsky told the jury they would hear from Bannon, who was chief executive of the Trump campaign and went on to work at the White House. This sets the stage for the most high-profile and bruising scrutiny yet of the inner workings of the 2016 Trump campaign, months after the Russia investigation led by special counsel Robert Mueller wound up.

Zelinsky said the court will also hear from the former deputy campaign chairman Rick Gates, who testified for the government last year in a trial that led to the conviction of the former campaign chairman Paul Manafort.

Unlike previous court cases related to senior figures in the president’s orbit, Trump’s name was cited frequently in Zelinsky’s opening statement before US district court Judge Amy Berman Jackson – including an allegation that he was in direct contact with Stone as the latter pursued hacked emails to hurt Clinton.

“Now you’ll ask, why didn’t Roger Stone just tell the truth?” Zelinsky told jurors as the 67-year-old defendant, sitting at a desk behind him, looked on. “The evidence in this case will show that Roger Stone lied to the House intelligence committee because the truth looked bad. The truth looked bad for the Trump campaign, and the truth looked bad for Donald Trump.”

Stone, who has a tattoo of former president Richard Nixon on his back, has been a confidant of the current US president for 40 years.

Zelinsky said that in July 2016, Stone spoke by phone with Trump for about 10 minutes. About an hour later, he alleged, Stone told his associate Jerome Corsi in an email “that a friend of theirs living in London should see Julian Assange”. Two days later, Corsi wrote back and said their friend planned two more disclosures of hacked emails.

Zelinsky continued: “Stone regularly updated people on the Trump campaign at the senior levels about whatever information he thought he had about WikiLeaks. [He] was going to the very top of the Trump campaign – the CEO of the Trump campaign – a man named Steve Bannon.”

The contacts continued until close to election day as Trump struggled in the opinion polls. According to the prosecutor, “Roger Stone emailed campaign chairman Paul Manafort to save, in Stone’s words, ‘Trump’s ass’. And he emailed Bannon about a way he had to win this but ‘it wasn’t pretty’.”

The prosecutor argued that Stone relied on Corsi and conservative radio host Randy Credico as intermediaries with the WikiLeaks founder, Julian Assange, although he later lied about the sequence of events and tried to make Credico the fall guy.

But as House investigators closed in, Stone pressured Credico to cover his tracks. He threatened him and even his dog. He also asked him to “do a Frank Pentangeli”, a reference to a character in The Godfather Part II who falsely claims he cannot remember anything.

Stone also told Credico not to comply with special counsel Robert Mueller’s investigation. In an email on 25 January last year, Stone wrote to Credico: “Waste of your time – tell him to go fuck himself.” Credico replied: “Who?” Stone said: “Mueller.”

Stone has pleaded not guilty to charges of obstructing justice, witness tampering and lying to the committee.

Stone’s defence lawyer, Bruce Rogow, defended his client’s contacts with Bannon, Gates and the defence contractor Erik Prince. “We’ll let the evidence reflect what those relationships were and whether there was any corrupt intent in it,” he said.



What linked the group, he argued, was a combined effort to get Trump elected. “That is not a crime.”



Rogow pleaded with the jury to consider the context of Stone’s testimony to the House intelligence committee. “We are talking about his state of mind that the Russians did not collude with him or with the Trump campaign, and that’s how he goes into this,” Rogow said.

The first witness called by the prosecution was Michelle Taylor, a former FBI agent who worked on the case. She testified that on 14 June 2016, the day the Washington Post reported Russian government hackers had penetrated the computer network of the Democratic National Committee, there were three phone calls between Trump and Stone. The content of the calls is unknown.

Taylor also described emails between Stone, Corsi, Credico, Bannon, Manafort and Prince that suggested a politically crucial WikiLeaks dump was imminent. Credico sent a text on 3 October 2016 to Stone that alleged Clinton “will kill without conscience the same way Luca Brasi did” – another Godfather reference. Credico also sent photos of himself outside the Ecuadorian embassy in London, where Assange was holed up.

Sitting in court, Stone looked at the exhibits as they were displayed on computer monitors, sometimes taking handwritten notes.

The case resumes at 9.30am on Thursday.