If nothing else, the trial of Donald Trump in the US Senate will afford teachers of game theory a case study for the age. It is in the collective interest of sensible Republicans in that chamber to convict the former president over last month’s Capitol siege. It is in no individual senator’s interest to taste the ensuing wrath of his fans. Republicans must either co-ordinate to pool their risk — they can’t all be hounded — or let Trump off. He can book his acquittal party now.

The likeliest volunteer for the torment of going against Trump is Utah senator Mitt Romney. No one who sought converts to Mormonism in 1960s France is unacquainted with thankless work. The most prominent latter-day saint in the US remains a glutton for it. Last February, Romney alone among Republican senators voted to remove Trump over his dealings with Ukraine. Of late, he has stressed the legitimacy of convicting a former president. Elliptically, he wants a “meaningful consequence” for the incitement of violence on January 6.

If there is a future for US conservatism beyond hot-tempered quackery, Romney points the way. What marks him out as an agent for change is that he does not stop at a moral stand against Trump. He also questions the small-government bias of a party that has let its economic views become articles of faith. His break with Republican convention is as doctrinal as it is moral. Coming nine years after a stringently free-market (and duly failed) run for the White House, his apostasy is eye-catching.

So far, its most concrete expression is the Family Security Act he proposed last week. Romney wants to condense a fog of tax credits and fiscal transfers into a single benefit for households with children. The left-leaning People’s Policy Project, a think-tank, says it is more generous than President Joe Biden’s plan. Bucking a policy trend since the 1990s, it is not conditional on a parent being in work. A rare consolation for the right is its removal of the so-called tax penalties against marriage.

It is not just liberals of a cosmopolitan sort who will chafe at the pro-natalism. Given what is known of the climate impact of each new life, strict environmentalists might too. Only a churl, though, would deny the progressive intent. Here is a Republican with hard cash for low-to-middle earners, not just cultural flattery. The more the party offers of the first, the less it need count on the second. More bread should lead to fewer circuses. There is a neat circularity to the process of Republican reform.

If Americans take a jaundiced view of technocrats, it is not without historical cause. Herbert Hoover was a first-class administrator — in public and private realms — before his stint as the Depression’s Marie Antoinette. Rational to a fault, the president from 1929 to 1933 seemed cloth-eared to the wails of a suffering people. A generation later, Robert McNamara infused the defence department with the same mix of technical mastery and dire judgment. This sublime quant, the first president of the Ford Motor Company from outside the Ford family, helped to botch the Vietnam war.

In 2012, voters had Romney pegged as the heir to this grand tradition of competent fools. Plainly, the co-founder of Bain Capital, the vaunted salvager of the 2002 winter Olympics, would have run a tight ship. But perhaps too tight. No one who wrote off 47 per cent of the nation as wards of a soft-touch government was presidential fibre.

This is what gives drama and even poignancy to (the former missionary will have to excuse the phrase) his conversion. He is moving beyond his party’s impoverished concept of “freedom” as something inversely proportional to one’s annual tax liability. Lots of anti-Trump conservatives stop short of that. Their dream is a better-behaved frontman or woman for roughly the same ideas that left the party so ripe for populist capture in 2016.

A veteran of private equity, Romney is not going to make the Grand Old Party his last corporate turnround job. Too many of his colleagues are incorrigible, as Trump’s near-certain acquittal implies. Despite that ageless sheen, at 73 the senator is also likely to be too old.

What he might achieve is to serve as the model for whoever does one day redeem the party. For a Republican, denouncing Trump is brave, in the all too physical sense. But it is also howlingly obvious.

It is the design of a new, more rounded conservatism that requires difficult thought. Romney is doing some of both. It is one of the better second acts in American lives.

Follow Janan Ganesh with myFT and on Twitter