Donald Trump’s second attorney general, William Barr, told the former US president he was “like a bull in a bull ring” and “someone’s going to come and put a sword through your head”. In return, Trump called Barr a “horse” who had been “broken” by the radical left. Such was the state of debate in the upper echelons of the Republican party on Monday as it digested the latest round of promotion of Barr’s memoir, One Damn Thing After Another. The book will be published on Tuesday but it has been extensively trailed – including by the Guardian. On the page and in interviews, Barr says Trump is unfit for the presidency and should not be the Republican nominee in 2024. But Barr remains a staunch conservative. On Monday, he told NBC’s Today that despite it all, if Trump was the Republican nominee in 2024, he would vote for him. “Because I believe that the greatest threat to the country is the progressive agenda being pushed by the Democratic party, it’s inconceivable to me that I wouldn’t vote for the Republican nominee,” Barr said. In his book, Barr repeatedly describes disagreements with Trump and tactics used by senior aides including the then secretary of state, Mike Pompeo, to distract or obstruct the erratic and often furious president. Speaking to NPR on Monday, Barr repeated a passage in his book when he said: “At one point, I said to [Trump]: ‘You know, Mr President, you’re like a bull in a bull ring and your adversaries have your number. They know how to get under your skin, and all they have to do is wave a red flag over here and you go charging and attack it.’ “And I said, ‘At the end of the day, you’re going to be in the middle of the ring sweating and someone’s going to come and put a sword through your head. “He didn’t think much of that metaphor.” Trump evidently no longer thinks much of Barr. This weekend, the former president wrote a lengthy letter to Lester Holt, an NBC anchor who interviewed Barr on TV. “Bill Barr cares more about the corrupt Washington media and elite than serving the American people,” Trump wrote, as reported by Axios. “He was slow, lethargic, and I realised early on that he never had what it takes to make a great attorney general. When the radical left Democrats threatened to hold him in contempt and even worse, impeach him, he became virtually worthless for law and order and election integrity. They broke him just like a trainer breaks a horse.” Trump also said: “I would imagine that if the book is anything like him, it will be long, slow and very boring.” Critics might disagree. Reviewing the book for the Washington Post, Devlin Barrett said Trump’s second attorney general “was easily [his] most effective and important cabinet member” and Barr’s memoir showed he could “tell a good yarn and has a penchant for deadpan punchlines”. That said, Barrett wrote, Barr had really written “a defense of his tenure to fellow conservatives”. “Barr bided his time before taking one last swing,” Barrett said. “But as long as there are senior officials like Barr, there will be presidents like Trump.” The book has produced a flood of media attention, including charges that Barr is seeking to whitewash his role in some of Trump’s most controversial moments. Barr defends his handling of the investigation of Russian election interference and links between Trump and Moscow. In particular, he focuses on his decision to release a summary of the report by Robert Mueller. In that letter, Barr cleared Trump of seeking to obstruct justice despite the special counsel laying out 10 possible instances of such potentially criminal behavior. Speaking to NBC, Barr repeated his conclusion that Trump’s claims of voter fraud in his defeat by Joe Biden were baseless – he has used the word “bullshit” – while skating over criticism for using the Department of Justice to investigate such lies. He said Trump was “responsible in the broad sense of that word” for the deadly Capitol riot over which he was impeached a second time, for inciting an insurrection. “It appears that part of the plan was to send this group up to the Hill,” Barr said, of the storming of Congress by Trump supporters around which seven people died. “I think the whole idea was to intimidate Congress. And I think that that was wrong.” But he also said: “I haven’t seen anything to say he was legally responsible for it in terms of incitement.” Barr also addressed an incident he left out of his book: the firing of a US attorney, Geoffrey Berman, who was supervising investigations of Trump associates and business affairs as well as an investigation of a Turkish bank which the Turkish president asked Trump to drop. “I didn’t think there was any threat to the president,” Barr told NBC, adding that the decision “was my call”. “I hadn’t really thought much of him,” he said. “I wanted to make the change.”