John Bolton has said Donald Trump told him last summer that he wanted to continue to freeze military aid to Ukraine until it agreed to launch a probe into Joe Biden and his son.

The former national security advisor reportedly made the claim in an as yet unpublished manuscript, currently doing the rounds in Washington DC, and a copy of which has sent to the White House for standard vetting.

The New York Times said that in the document, which it does not quote from directly, Mr Bolton reveals over the space of dozens of pages how the Ukraine scandal played out until the left the administration in September.

He said that, in August, Mr Tump told him he wanted to continue to freeze almost $400m in security assistance to Ukraine assigned by Congress to help Kiev confront the threat from Russia until it announced it was looking into allegations of corruption concerning the former vice president and his son.

Details of the manuscript emerged with Mr Trump’s lawyers set to continue their defence of the president, as the Senate considers two articles of impeachment passed last year by the House of Representatives.

All the president's lawyers: The team fighting Trump's impeachment Show all 6 1 /6 All the president's lawyers: The team fighting Trump's impeachment All the president's lawyers: The team fighting Trump's impeachment Alan Dershowitz Dershowitz is a controversial American lawyer best known for the high-profile clients he has successfully defended. Those clients have included OJ Simpson, Jeffrey Epstein and Harvey Weinstein. One longtime Harvard Law associated told the New Yorker Dershowitz "revels in taking positions that ultimately are not just controversial but pretty close to indefensible." Getty All the president's lawyers: The team fighting Trump's impeachment Ken Starr Starr became a household name in the 1990s as the independent counsel who led the investigation that led to Bill Clinton's impeachment. That investigation began as a look into a real estate scandal known as Whitewater, and eventually led to impeachment after Mr Clinton lied under oath about having an affair with White House intern Monica Lewinsky. AP All the president's lawyers: The team fighting Trump's impeachment Jay Sekulow Sekulow is the president's longtime personal attorney, and, now, personal lawyer in the White House. He has been accused by former Rudy Giuliani associate Lev Parnas of being "in the loop" during the Ukraine scandal. Getty All the president's lawyers: The team fighting Trump's impeachment Pam Bondi Bondi is the former attorney general in Florida, and a longtime backer of the president's. She made a name for herself in Florida for taking hyper partisan stances on issues, and her penchant for publicity. She is likely to be a prominent public-facing figure during the trial. AFP/Getty All the president's lawyers: The team fighting Trump's impeachment Pat Cipollone Cipollone is the White House counsel, and leading the president's defence team. Getty All the president's lawyers: The team fighting Trump's impeachment Rudy Giuliani While not officially named as one of the president's impeachment lawyers, it is hard to ignore Giuliani's outsized role in this process. The former mayor of New York has been making headlines for months as he defends his client, and for his apparent role in the effort to compel Ukraine to launch the investigation into Joe Biden. We'll see how he figures in the actual trial, which he has said he would like to be a part of. Reuters

Mr Bolton’s comments, apparently undercutting the president’s claim that the military aid was not linked to to a quid pro quo, have the power to be especially damaging given Mr Bolton’s status as someone who was until very recently at the heart of the Trump administration’s foreign policy world.

It may also explain why Mr Trump and Republicans have sought not to permit Mr Bolton to testify, and why Democrats are so keen to hear from him.

Last week, Mr Trump told reporters he did not want Mr Bolton to appear and said that even if he simply spoke in public it could damage national security.

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“The problem with John is it’s a national security problem,” Mr Trump said at Davos, Switzerland. “He knows some of my thoughts. He knows what I think about leaders. What happens if he reveals what I think about a certain leader and it’s not very positive?” He added: “It’s going to make the job very hard.”

The manuscript apparently also claims that secretary of state Mike Pompeo conceded in private to Mr Bolton there was no basis to claims by Mr Trump’s personal lawyer, Rudy Giuliani, that the then US ambassador to Ukraine, Marie Yovanovitch, was corrupt.

Ms Yovanovitch, who had a reputation for fighting corruption, was abruptly recalled in May 2019 after a whispering campaign against her.

This week an audio tape emerged in which Lev Parnas, an associate of Mr Giuliani, can be heard telling the president at a dinner in April 2018 that Ms Yovanovitch had been bad-mouthing him, suggesting he was going to be impeached. A voice believed to be that of Mr Trump then says: “Get rid of her. Get her out tomorrow. I don’t care. Get her out tomorrow. Take her out. OK? Do it.”

It was reported that another associate of Mr Giuliani, former US Marine Robert Hyde, claimed to have had Ms Yovanovitch under surveillance, although he later said he was joking.

In his 25 July phone call to the Ukrainian president, which sparked the impeachment investigation, Mr Trump appears to threaten the former ambassador, saying: “Well, she’s going to go through some things.”

Mr Pompeo recently erupted at a reporter when asked about whether he owed Ms Yovanovitch an apology. She was withdrawn early from her position and testified to the House that she felt intimated by the comments made about her by Mr Trump and Mr Giuliani.

Reuters said the White House had yet to respond to the claims made by Mr Bolton, and neither had Jay Sekulow, helping lead Mr Trump’s legal defence in his impeachment trial.

Charles Cooper, a lawyer representing Mr Bolton, did not respond to a request for comment.