Many people hate Hillary Rodham Clinton. She has long been the target of deep-seated misogyny, exemplified by chants of ‘Lock her up!’ at Trump rallies during the 2016 presidential campaign. I say this as someone who has never been much of a fan, stretching back to the days when she defended her ghastly husband during the impeachment crisis of 1998. I was relieved when she launched her own political career, becoming in turn a senator, secretary of state and the first female presidential candidate with a real chance of winning. Even so, it’s not far short of tragic to watch an intelligent woman sticking with a man who has humiliated her so often. Why on earth has she put up with him? And what might her own career have been like if she had stayed Hillary Rodham? The American author Curtis Sittenfeld takes on the second of these what-ifs in her new novel, starkly entitled Rodham.

Sittenfeld’s previous books include American Wife, featuring a character based on the former first lady Laura Bush. Sittenfeld sets up a bold counterfactual: Rodham has the young Hillary Rodham, a brilliant law student from Chicago, meeting and falling in love with a shambling but charismatic fellow student from Arkansas – but although they have a relationship, she doesn’t marry him. Sittenfeld’s Bill Clinton is bear-like and a persistent suitor, flattering Hillary’s intellect and manipulating her anxieties about her physical appearance. Their sexual encounters are described in squirm-inducing detail, but it’s clear that Sittenfeld is working hard to show how a clever but insecure woman might be drawn to a less talented but vastly more confident man.

Bill and Hillary are very much children of their time, beneficiaries of the upheavals of the 1960s, which broke down all sorts of social and political barriers. It’s still easier for Bill than Hillary, who endures endless slights from her own father and struggles to be taken seriously in her career, while Bill steams confidently ahead. There is another difference: Bill embraces the sexual revolution, grabbing all the sex he can get, something Hillary realises only when she discovers he’s sleeping with her boss’s teenage daughter.

The fictional Hillary has internalised the desperately damaging notion that clever women can’t be sexy, and the realisation that Bill has been serially unfaithful appears to confirm her feeling that she will never really be desired. Some of the novel’s most painful passages come when Hillary tries to reason with herself, toying with the threadbare fiction that such an attractive man can’t help being unfaithful; it’s a series of contortions that other women have no doubt gone through in similar circumstances. But their relationship comes to a messy end after an unsuccessful early election campaign in Arkansas, when a campaign aide seeks Hillary out in a car park and accuses the fictional Bill of rape.

Of course, it is impossible to know whether the real-life Hillary went through intense internal debates before marrying Bill (she did once make the uncomfortable observation that she always knew he would be ‘a hard dog to keep on the porch’). Sittenfeld’s characterisation of Bill as a charming narcissist, turning a brief but irresistible beam of attention on one woman after another, is convincing and compelling; at the same time, it owes a great deal to a modern grasp of how serial seducers operate, which wasn’t widely understood even as recently as the 1990s. I’m still astounded by how many cultural and political heavyweights, including some avowed feminists, defended the real President Clinton when his sexual exploitation of a White House intern came to light; whether he would emerge unscathed in the age of #MeToo from a stream of revelations about his alleged abuse of women is another matter. In that sense, Sittenfeld’s novel benefits from hindsight, regarding events in the 20th century from the standpoint of the 21st, which is less tolerant of appalling male behaviour.

In the book, Hillary breaks off her engagement following a great deal of soul-searching, hoping for months that Bill will get in touch to talk her out of it. When he doesn’t, Sittenfeld is left with an imaginative challenge: how to make her Hillary, who is so closely associated in everyone’s minds with Bill Clinton, into an interesting and credible character over the next half-century. The real woman has remained quite private, despite publishing several volumes of memoir, and Sittenfeld tries to infer aspects of her character from Hillary’s handling of events in her public life. In the novel, she is almost unbearably earnest, perpetually racked by anxiety about her appearance, and the rest of the book resembles nothing so much as a very extended CV. There are a few mishaps on the campaign trail and Hillary shows occasional flashes of ruthlessness, but it’s hard going after the vivid early chapters.

The notion of a parallel universe in which Hillary keeps her own name and identity is beguiling. Yet the author cannot quite bring herself to complete the separation of this well-known couple, repeatedly bringing Bill, who becomes a tech billionaire, back into Hillary’s orbit. This has the perverse effect of turning Hill-without-Bill into a sad stereotype, a woman whose stellar career is a consolation prize for the loss of a dazzling first love. Sittenfeld endows her Hillary with the guts to dump a serial shagger – three cheers for that! – but it would have been much more interesting if she’d also allowed her to get over him.