Many years ago, when the earth was young and leaving the European Union was a position espoused only by those trying to stay on the right side of Bill Cash at a drinks party, Ken Clarke stood for the Tory leadership against Iain Duncan Smith. He said one memorable thing while making his doomed bid for the captaincy – which was that the Tories needed to decide whether they were going to be a political party or a debating society.

What I understand him to have meant by that was that ideological purity buttered no parsnips in politics. For most of its history, its friends and its enemies alike would agree that the Conservative party has been a magnificent machine for winning and retaining power. While the Left frittered its energy denouncing ideological deviationists, reciting parrot-like dogmas about collective ownership, and purging its own ranks, Tories were pragmatists. They believed something firmly until it became a vote-loser; and then they found a way of believing something else. I don’t say that as a sneer but as a sincere compliment. Toryism has tended to recognise that there’s no point in having a brilliant scheme for government if you can’t get into government in the first place. Tony Blair struck gold when he had the humility to copy that page of his rivals’ homework.

Liz Truss, on the face of it, has been doing the same thing. She can’t invent and promulgate Trussism until she has her bottom planted on Boris Johnson’s old chair in No. 10. And she can’t plant her bottom thither without the support of the 160,000-odd paid-up members of the Conservative party who have been voting for the next leader. So far, so good. She is on the case, and how.

Some people grumble that her policy platforms have been a bit vague, and what specifics we have had – such as her hastily revised scheme to cut public sector pay – are getting pushback from the supposed experts. One police chief has called her policing policy ‘meaningless’. Economists at the OBR and the IFS have been sceptical about her confidence that all it will take is a few tax cuts to put a tiger back in the national tank. She has pledged to help those about to be clobbered by rocketing energy bills, though she’s done so by promising what you might describe as ‘an undertaking of great advantage, but nobody to know what it is’.

A defence can be made there – and has been – that Truss is doing what politicians always do: she is campaigning in poetry that she might govern in prose. You come up with a series of resonant slogans that don’t tie you down to a specific policy position – ‘Build Back Better’, ‘I’m Backing Britain’, ‘For the Many, Not the Few’, or what have you – wave a few flags and hope for the best. Once you’ve promised your core supporters the moon, you set about gently revising their expectations after you’re safely ensconced in the reality-based world of actual government.

I don’t, by the way, presume here to editorialise on why a Truss premiership would be a Bad Thing, still less to describe the horrible face I made as I read the list of her rumoured cabinet appointments. Obviously Liz Truss isn’t specially interested in appealing to soaking wet liberal centrist dads like me – and fair enough. That’s not the game she’s in. She might throw the likes of us a bone come a general election, but we’re a way off that yet. If people like me are complaining that she wants to cut taxes so people can keep more of their own money, rather than spend other people’s money on handouts to the needy, that’s probably a sign she’s doing something right by her natural constituency.

But it’s that natural constituency that I worry about. The Tory selectorate does indeed seem to love her to pieces. The papers over the last few weeks have been full of graphs in which her chances of winning go roaring up the Y-axis like Jeff Bezos heading into near earth orbit. But – unless that selectorate is a minority of ideologues with a very narrow and idiosyncratic set of obsessions – you’d expect their instincts to overlap a good deal with the wider population of Conservative voters. You would certainly not expect paid-up party members to love Liz Truss more and more the more they see of her while at the same time civilian voters of a broadly conservative stripe take the opposite trajectory.

Yet that is what seems to be happening. A poll by Opinium of people who had voted Conservative in the 2019 election discovered that where in early August just under half of them thought she looked like a prime minister in waiting, by the end of the month less than a third still thought so. Of these voters, 55 per cent thought she was competent at the start of the month; 35 per cent thought so at the end. More than half thought her likeable at the start of the month; 31 per cent thought so just a few weeks later. And so on. Those are the people whose tummies any successful candidate should at this point be finding it relatively easy to tickle. If she really is campaigning in poetry, these findings indicate that it’s Vogon poetry.

Perhaps we dismiss this poll as an outlier – and not knowing the sample size or methodology, it’s only right to be cautious. There are lots of ways that a poll of Tory voters might skew differently to the Tory membership: the last election, like any election in which one party clinches a big majority, represented a broad coalition of interests. Who’s to say the pollsters didn’t consult a disproportionate number of single-issue voters who hopped on the Boris bus in 2019 and are on the point of hopping back off? And yet and yet. Twenty per cent swings in a month? That’s quite the rounding error. A ten per cent swing, a five per cent swing… even a sullen refusal to show more enthusiasm over the course of the campaign would be concerning. Wouldn’t it?

This may not in any way be a strike against Liz Truss. But it is a problem for her. If the membership really does adore things that put ordinary Conservative voters off their toast and marmalade, that’s a sign that power over the leadership is in the hands of people who don’t much care about winning the next election; people, in other words, who prefer to be a debating society. And you don’t have to reach back to Clarke versus Duncan Smith for a parallel. Labour found itself in exactly that position when, thanks to its join-the-party-for-a-fiver scheme, its membership was taken over by hard-left ultras who set about making the whole party completely unelectable. If that’s what is happening here, Ms Truss – Lord help her – may end up not being the 21st-century’s Mrs Thatcher so much as the Tory party’s Jeremy Corbyn.