When Fox News called Arizona for Joe Biden on election night 2020, infuriating Donald Trump and fueling Republican election subversion attempts which continue to this day, Rupert Murdoch told Jared Kushner “the numbers are ironclad – it’s not even close”.

Details of the Fox News owner’s conversation with Trump’s son-in-law and chief adviser about the call which most observers say confirmed Trump’s defeat are contained in Kushner’s memoir, Breaking History, which is due out next month.

They also come as Murdoch-owned papers and even Fox News itself seem to turn against Trump in light of the January 6 hearings on the US Capitol attack and his attempt to overturn his election defeat.

A first extract from the book, in which Kushner described being secretly treated for thyroid cancer, was reported by Maggie Haberman of the New York Times.

On Wednesday another Times reporter, Kenneth Vogel, tweeted pictures of pages from Kushner’s book, each emblazoned with the word “confidential”.

Kushner’s description of the shock of the Fox News Arizona call mirrors those in numerous reports and books on Trump’s 2020 defeat, his refusal to accept it and the attack on US democracy which followed.

“The shocking projection brought our momentum to a screeching halt,” Kushner writes. “It instantly changed the mood among our campaign’s leaders, who were scrambling to understand the network’s methodology.”

Kushner describes the Trump campaign’s focus on Arizona and writes that losing there “would drastically narrow our path to victory”.

In Landslide, a book released last year, the author Michael Wolff reported that Murdoch gave his son Lachlan Murdoch approval for Fox News to call Arizona for Biden with “a signature grunt” and a barb for Trump: “Fuck him.”

Fox News denied Wolff’s story.

Kushner writes: “I dialed Rupert Murdoch and asked why Fox News had made the Arizona call before hundreds of thousands of votes were tallied. Rupert said he would look into the issue, and minutes later he called back.

“‘Sorry Jared, there is nothing I can do,’” he said. “‘The Fox News data authority says the numbers are ironclad – he says it won’t be close.’”

Biden won Arizona by about 10,000 votes, a margin which increased after a partisan audit encouraged by Trump allies and commissioned by state Republicans.

Key members of the Fox News decision desk left after the election. Chris Stirewalt, the politics editor, was fired. He has appeared before the January 6 committee.

“We knew [Arizona] would be a consequential call because it was one of five states that really mattered,” Stirewalt testified.

Stirewalt also said that by the time of the Arizona call, Trump’s chances of beating Biden were “very small” and “getting smaller”. After Arizona, he said, those chances dwindled to “none”.

In his book, Kushner shades close to his father-in-law’s lie about electoral fraud in Biden’s victory, writing: “2020 was full of anomalies.”

The election was called for Biden on 7 November, when Pennsylvania fell into his column. He won the electoral college by 306-232, the same margin Trump called a landslide when it landed in his favour against Hillary Clinton in 2016. Biden won the popular vote by more than 7m.

In his passage on the speech Trump gave in the early hours of 4 November, the day after election day, claiming “Frankly, we did win this election”, Kushner says he was called by Karl Rove, the strategist who helped George W Bush win “the closest presidential election in US history”, against Al Gore in 2000.

Trump claimed to have been the victim of fraud. Rove, Kushner writes, said: “The president’s rhetoric is all wrong. He’s going to win. Statistically, there’s no way the Democrats can catch up with you now.”

Kushner says he responded: “Call the president and tell him that.”

Trump later turned on Rove, who he said called him at 10.30pm on election night “to congratulate me on ‘a great win’”. Fox News called Arizona just before midnight.

On Wednesday, Vogel also tweeted pages in which Kushner describes his work on presidential pardons.

Kushner says he did not oppose a pardon for Steve Bannon, the former Trump strategist who was accused of fraud but who was a prominent White House leaker, because of the work Bannon did on Trump’s winning campaign in 2016.

He also writes that when Trump pardoned Alice Johnson, a Black grandmother sentenced on a minor drugs-related charge of the sort Kushner targeted in his work on sentencing reform, Trump said: “Let’s hope Alice doesn’t go out and kill anyone!”