The White House counsel, Don McGahn, has co-operated extensively in the special counsel investigation, sharing detailed accounts about the episodes at the heart of the inquiry into whether President Donald Trump obstructed justice, including some that investigators would not have learned of otherwise, according to a dozen current and former White House officials and others briefed on the matter.

In at least three voluntary interviews with investigators that totalled 30 hours during the past nine months, Mr McGahn described the President’s fury toward the Russia investigation and the ways in which he urged Mr McGahn to respond to it. He provided the investigators examining whether Mr Trump obstructed justice a clear view of the President’s most intimate moments with his lawyer.

Among them were Mr Trump’s comments and actions during the firing of former FBI director James Comey and Mr Trump’s obsession with putting a loyalist in charge of the inquiry, including his repeated urging of Attorney General Jeff Sessions to claim oversight of it.

Mr McGahn was also centrally involved in Mr Trump’s attempts to fire the special counsel, Robert Mueller, which investigators might not have discovered without him.

For a lawyer to share so much with investigators scrutinising his client is unusual. Lawyers are rarely so open with investigators, not only because they are advocating on behalf of their clients but also because their conversations with clients are potentially shielded by attorney-client privilege, and in the case of presidents, executive privilege.

“A prosecutor would kill for that,” said Solomon Wisenberg, a deputy independent counsel in the Whitewater investigation, which did not have the same level of co-operation from President Bill Clinton’s lawyers. “Oh my God, it would have been phenomenally helpful to us. It would have been like having the keys to the kingdom.”

Mr McGahn’s co-operation began in part as a result of a decision by Mr Trump’s first team of criminal lawyers to collaborate fully with Mr Mueller. The President’s lawyers have explained they believed their client had nothing to hide and that they could bring the investigation to an end quickly.

Mr McGahn and his lawyer, William Burck, could not understand why Mr Trump was so willing to allow Mr McGahn to speak freely to the special counsel and feared Mr Trump was setting up Mr McGahn to take the blame for any possible illegal acts of obstruction, according to people close to him. So he and Mr Burck devised their own strategy to do as much as possible to co-operate with Mr Mueller to demonstrate that Mr McGahn did nothing wrong.

It is not clear that Mr Trump appreciates the extent to which Mr McGahn has co-operated with the special counsel. The President wrongly believed that Mr McGahn would act as a personal lawyer would for clients and solely defend his interests to investigators, according to a person with knowledge of his thinking.

In fact, Mr McGahn laid out how Mr Trump tried to ensure control of the investigation, giving investigators a mix of information both potentially damaging and favourable to the President. Mr McGahn cautioned to investigators that he never saw Mr Trump go beyond his legal authorities, though the limits of executive power are murky.

Mr McGahn is guiding the Supreme Court pick, Brett Kavanaugh, left, through his confirmation. Photo: Al Drago / NYT

Mr McGahn’s role as a co-operating witness further strains his already complicated relationship with the President. Though Mr Trump has fought with Mr McGahn as much as with any of his top aides, White House advisers have said, both men have benefited significantly from their partnership.

Mr McGahn has overseen two of Mr Trump’s signature accomplishments – stocking the federal courts and cutting government regulations – and become a champion of conservatives in the process.

But the two rarely speak one on one — White House Chief of Staff John Kelly and other advisers are usually present for their meetings — and Mr Trump has questioned Mr McGahn’s loyalty. In turn, Mr Trump’s behaviour has so exasperated Mr McGahn that he has called the President “King Kong” behind his back, to connote his volcanic anger, people close to Mr McGahn said.

This account is based on interviews with current and former White House officials and others who have spoken to both men, all of whom requested anonymity to discuss a sensitive investigation. A spokesman for the special counsel’s office also declined to comment for this article.

Mr Burck said Mr McGahn had been obliged to co-operate with the special counsel. “President Trump, through counsel, declined to assert any privilege over Mr McGahn’s testimony, so Mr McGahn answered the special counsel team’s questions fulsomely and honestly, as any person interviewed by federal investigators must,” he said.

Asked for comment, the White House sought to quell the sense of tension.

“The President and Don have a great relationship,” the White House press secretary Sarah Huckabee Sanders said in a statement. “He appreciates all the hard work he’s done, particularly his help and expertise with the judges, and the Supreme Court” nominees.

The President stressed that the White House had been co-operative with the investigation, tweeting after this article was published that Mr McGahn had been allowed to speak to the special counsel.

I allowed White House Counsel Don McGahn, and all other requested members of the White House Staff, to fully cooperate with the Special Counsel. In addition we readily gave over one million pages of documents. Most transparent in history. No Collusion, No Obstruction. Witch Hunt!

— Donald J. Trump (@realDonaldTrump) August 18, 2018

Mr McGahn’s route from top White House lawyer to a central witness in the obstruction investigation of the President began around the time Mr Mueller took over the investigation into whether any Trump associates conspired with Russia’s interference in the presidential election.

When Mr Mueller was appointed in May 2017, the lawyers surrounding the President realigned themselves. Mr McGahn and other White House lawyers stopped dealing on a day-to-day basis with the investigation, as they realised they were potential witnesses in an obstruction case.

In the following weeks, Mr Trump assembled a personal legal team to defend him. He wanted to take on Mr Mueller directly, attacking his credibility and impeding investigators. But two of his newly hired lawyers, John Dowd and Ty Cobb, have said they took Mr Trump at his word that he did nothing wrong and sold him on an open-book strategy. As long as Mr Trump and the White House co-operated with Mueller, they told him, they could bring an end to the investigation within months.

Mr McGahn, who had objected to Mr Cobb’s hiring, was dubious, according to people he spoke to around that time. As White House counsel, not a personal lawyer, he viewed his role as protector of the presidency, not of Mr Trump. Allowing a special counsel to root around the West Wing could set a precedent harmful to future administrations.

Though he was a senior campaign aide, it is not clear whether Mr Mueller’s investigators have questioned Mr McGahn about whether Trump associates co-ordinated with Russia’s effort to influence the election.

Mr McGahn’s decision to co-operate with the special counsel grew out of Mr Dowd and Mr Cobb’s game plan, now seen as misguided by some close to the president.

In fall 2017, Mr Mueller’s office asked to interview Mr McGahn. To the surprise of the White House Counsel’s Office, Mr Trump and his lawyers signalled they had no objection, without knowing the extent of what Mr McGahn was going to tell investigators.

Mr McGahn was stunned, as was Mr Burck, whom he had recently hired out of concern that he needed help to stay out of legal jeopardy, according to people close to Mr McGahn. Mr Burck has explained to others that he told White House advisers that they did not appreciate the President’s legal exposure and that it was “insane” that Mr Trump did not fight a McGahn interview in court.

Mr McGahn’s relationship with the President soured as Mr Trump blamed him for a number of fraught moments in his first months in office. Photo: Doug Mills / NYT

Even if the President did nothing wrong, Mr Burck told White House lawyers, the White House has to understand that a client like Mr Trump probably made politically damaging statements to Mr McGahn as he weighed whether to intervene in the Russia investigation.

Inside the counsel’s office, lawyers feared that on the recommendation of Mr Dowd and Mr Cobb, the White House was handing Mr Mueller detailed instructions to take down the President and setting a troubling precedent for future administrations by giving up executive privilege.

At the same time, Mr Trump was blaming Mr McGahn for his legal woes, yet encouraging him to speak to investigators. Mr McGahn and his lawyer grew suspicious. They began telling associates that they had concluded that the President had decided to let Mr McGahn take the fall for decisions that could be construed as obstruction of justice, like Mr Comey’s firing, by telling the special counsel that he was only following shoddy legal advice from Mr McGahn.

Worried that Mr Trump would ultimately blame him in the inquiry, Mr McGahn told people he was determined to avoid the fate of the White House counsel for President Richard Nixon, John Dean, who pleaded guilty to conspiracy to obstruct justice in the Watergate scandal.

Mr McGahn decided to fully co-operate with Mr Mueller. It was, he believed, the only choice he had to protect himself.

Unencumbered, Mr Burck and Mr McGahn met the special counsel team in November for the first time and shared all that McGahn knew.

To investigators, Mr McGahn was a fruitful witness, people familiar with the investigation said. He had been directly involved in nearly every episode they are scrutinising to determine whether the President obstructed justice. To make an obstruction case, prosecutors who lack a piece of slam-dunk evidence generally point to a range of actions that prove that the suspect tried to interfere with the inquiry.

Mr McGahn gave Mr Mueller’s investigators, the people said: a sense of the President’s mindset in the days leading to the firing of Mr Comey; how the White House handled the firing of former national security adviser Michael Flynn; and how Mr Trump repeatedly berated Mr Sessions, tried to get him to assert control over the investigation and threatened to fire him.

Despite the insistence of Mr Trump’s lawyers that co-operation would help end the inquiry, the investigation only intensified as 2017 came to a close. Mr Mueller had charged Mr Trump’s former campaign chairman and his deputy and won guilty pleas and co-operation agreements from his first national security adviser and a campaign adviser.

– The New York Times