To use the hot political word of the moment, Nancy Pelosi’s The Art of Power is a pretty weird kind of memoir, neither fish nor fowl. It would, she tells us in her acknowledgments, take another book to relate her amazing rise from “housewife [and mother of five] to House member to House speaker”, her long journey “from Baltimore to San Francisco”. In this volume, one eye on posterity, she prefers to look mostly at the part she played in major political events during the more than two decades she spent at the top of the Democratic party. But fear not: it’s all (a bit) less dry than it sounds. If I struggled to stay awake during her painstaking description of the battle to pass the Affordable Care Act of 2010 – quiz me later! – I was gripped by her hour-by-hour account of the attack on the US Capitol in 2021.

Who knew that on that shocking day some representatives were so sure they were about to die, they rang their families to say goodbye? That those with military training fashioned pikes from the wooden stands that held anti-Covid hand sanitiser in case they had to physically defend themselves? Pelosi is a Catholic, and the riot, as she notes, took place on the feast of the Epiphany, which celebrates the visit of the wise men to the infant Christ. But for the Republicans, revelations came there none. In the fullness of time, Donald Trump, for many akin to the riot’s puppeteer, became the party’s candidate for the presidency in spite of what some of them had seen with their own eyes on 6 January: the “stunning” violence that was all around; the fact that politicians had to make use, for the first time, of the gas masks that have been kept under seats in the Capitol’s two chambers since 9/11; the lingering memory, once it was all over, that the building stank to high heaven of human defecation.

Pelosi’s book was, of course, written long before Joe Biden stood down as the Democratic candidate, a decision in which she is said to have played a crucial role. It feels, in some senses, tardy and ill-timed; for British readers particularly, the acreage devoted to the Troubled Asset Relief Programme (Tarp) that was instituted by the US treasury after the 2008 financial crisis will seem somewhat beside the point when all our present interest lies in Kamala Harris and Tim Walz, and just how much they can wind Trump up.

But if I may permit myself such a violent analogy, Nancy chucks a few hand grenades in the direction of the election nonetheless. First, she holds Trump and his enablers responsible at one remove for the appalling attack on her husband, Paul. (In 2022, a far-right conspiracy theorist, David DePape, broke into the couple’s San Francisco house while Nancy, his target, was in Washington; Paul suffered three hammer blows to his head of such force that DePape later expressed surprise at his survival.) In recent years, she says, Republicans have spent millions of dollars on ads personally attacking her while, following the attack, Donald Trump Jr shared a meme of a hammer on social media that was captioned: “Got my Paul Pelosi Halloween costume ready.”

Second, she makes no bones about the fact she believes Trump Sr to be both dangerous and unstable. Her book begins with an account of her religious faith: she was, she writes, raised to be a nun by her mother; she looks for the “spark of divinity” in every human being she meets. But in the case of Trump, the pilot light of numinosity, if it ever existed, was extinguished long, long ago. Expectations of him, she writes, can never be low enough. The first time she met him after his election as president, he served pigs in blankets to Senator Chuck Schumer, blithely reassuring him they were kosher.

She regarded the whiny and “stupid” Trump throughout his time in office as “an impostor – and on some level, he knew it”. He was apt “surreptitiously” to listen in to meetings she had with his staff. If he was there in person, he often stormed out. At a funeral for a distinguished doctor of her acquaintance, numerous medics told her, unsolicited, “that they were deeply concerned… that his mental and psychological health was in decline”. Much later, on 8 January, 2021 (two days after the insurrection at the Capitol), she found herself so concerned by Trump’s erratic behaviour – impeachment was on the cards; she feared for the constitution if he was allowed to stay in office – that she rang the head of the joint chiefs of staff, General Mark Milley, seemingly seeking reassurance that the military, if given an order by the president to conduct a strike overseas, including a nuclear strike, “was not going to do anything illegal or crazy”.

It may be true that, as some American reviewers have noted, Pelosi isn’t much interested in self-criticism; nor does her book explain, even slightly, how an 84-year-old woman continues to exert such influence on the Democratic party (in addition to whatever she told the ailing Biden, she’s also said to have stumped for Walz, the Minnesota governor, to be Harris’s choice as vice-presidential candidate). Like all politicians everywhere, she falls back on, at best, sophistry and, at worst, willed blindness when it suits her. To British eyes, she cuts a slightly parodic figure, with her helmet blow dry and a face, tight and waxy, that now gives her an appearance of permanent surprise.

But The Art of Power, so sober and detailed, has brought me to reassess her. Her early campaigning work on Aids; her opposition to George Bush’s war in Iraq (“the most destabilising event in recent US history”); even her ability to see what vice-president Mike Pence did right, as well as wrong (he preferred to cower in a loading bay on the day of the Capitol riots than to be seen to leave the building). She is so formidable and, in certain circumstances, principled. What happens next remains to be seen. Even as Trump loses his mind – as I write, he is indulging in wild fantasies online in which Biden tries to take back the nomination – he’s still in a punchy electoral position. He could yet win. But if he doesn’t, Pelosi will surely be able to take at least some of the credit.