In a new memoir, the former US attorney general William Barr says Donald Trump must not be the Republican candidate for president in 2024.

The man he served between 2019 and 2020, Barr writes, has “shown he has neither the temperament nor persuasive powers to provide the kind of positive leadership that is needed”.

Trump, Barr says, has surrounded himself with “sycophants” and “whack jobs from outside the government, who fed him a steady diet of comforting but unsupported conspiracy theories”.

Trump hinted again on Saturday that he intends to run in 2024. He did not immediately comment on Barr’s analysis.

Last summer, though, he called his former attorney general a “swamp creature” and a “Rino [Republican in Name Only] … afraid, weak and frankly … pathetic”.

Barr’s book, One Damn Thing After Another: Memoirs of an Attorney General, will be published on 8 March, its title taken from a description of the job by Ed Levi, appointed by Gerald Ford after the Watergate scandal.

The Wall Street Journal, like publisher Harper Collins owned by Rupert Murdoch’s News Corp, first reported Barr’s book on Sunday. The New York Times and Washington Post followed suit.

A strong conservative, Barr was seen by most as a loyal servant to Trump, the second president he worked for after George HW Bush. The Massachusetts senator Elizabeth Warren was among those who thought Barr way too loyal, calling him “a disgrace” and “not a credible head of federal law enforcement”.

In his book, Barr rejects such accusations, prominently over the investigation of Russian election interference and links between Trump and Moscow.

Barr was accused of running interference for Trump, ultimately releasing a preemptory report summary which prompted an objection from the special counsel, Robert Mueller.

According to the Times, Barr calls claims he interfered “drivel” and says it was a “simple fact that the president never did anything to interfere with the special counsel’s investigation”.

Mueller, however, laid out extensive evidence of possible obstruction of justice by Trump, including the dangling of pardons. In his own report, the special counsel said he could not exonerate the president of trying to obstruct his work.

Regarding Michael Flynn, Trump’s first national security adviser who pleaded guilty to lying to the FBI about contacts with Russians, Barr writes: “Predictably our motion to dismiss the charges led to an election-year media onslaught, flogging the old theme that I was doing this as a favour to Trump.

“But I concluded the handling of the Flynn matter by the FBI had been an abuse of power that no responsible AG could let stand.”

A former judge appointed to review Barr’s move to dismiss disagreed, saying it was “clear evidence of a gross abuse of prosecutorial power” and represented “highly irregular conduct to benefit a political ally of the president”.

Flynn was eventually pardoned by Trump and became a key player in the attempt to overturn the 2020 election.

Barr also sought a more lenient sentence for the Trump ally Roger Stone, convicted of trying to obstruct the Russia investigation. Four prosecutors resigned but Barr insists in his book it was “reasonable” to act as he did. Stone’s sentence was ultimately commuted by Trump.

Barr also describes a previously reported Oval Office meeting on 1 December 2020, at which Trump pressed his lie about electoral fraud in his defeat by Joe Biden.

Barr had outraged many by using the Department of Justice to investigate Trump’s claims. But no evidence of widespread fraud was found and Barr used an interview with the Associated Press to say so.

The same day, according to Barr’s book, Trump shouted: “This is killing me – killing me. This is pulling the rug right out from under me.”

Echoing accounts of the meeting in Peril, by Bob Woodward and Robert Costa, and Betrayal, by Jonathan Karl, Barr says the president slipped into the third person.

“He stopped for a moment and then said, ‘You must hate Trump. You would only do this if you hate Trump.’”

Barr says he told Trump he had “sacrificed a lot personally to come in to help you when I thought you were being wronged”, but could not support the lie about electoral fraud.

After Trump listed other grievances, Barr offered to resign – an offer not reported by Karl or Woodward and Costa.

Trump, Barr writes, yelled “Accepted!”, banged his palm on a table and said: “Leave and don’t go back to your office. You are done right now. Go home!”

Barr says White House lawyers persuaded Trump not to allow him to quit. Barr finally resigned on 14 December, nearly two weeks later.

On 6 January 2021, after Trump spoke at a rally near the White House, the Capitol was attacked. Seven people died around the riot and more than 100 police officers were hurt. More than 700 people have been charged, 11 with seditious conspiracy. Trump was impeached, for inciting an insurrection.

In his book, Barr says: “The absurd lengths to which [Trump] took his ‘stolen election’ claim led to the rioting on Capitol Hill.”

But he also says Trump’s behaviour did not meet the legal standard for an incitement charge.