Sunflowers turn their yellow faces to the sun, moths fly toward flame, and people in politics gravitate towards power. It’s nothing personal, obviously; moths don’t even get what flames are, let alone particularly like them, or else they’d surely understand that the meeting of candle and sadly flammable insect rarely ends well. But they can’t seem to help themselves, and that explains an awful lot of what you’re going to see at Conservative party conference in Manchester, starting on Sunday.

This will be the first gathering of the Tory clan since the prime minister casually admitted to the BBC’s James Landale, while chopping vegetables in his kitchen, that he doesn’t actually fancy a third term much. And by publicly confirming what has long been an open secret in his circle, he’s effectively declared open season on himself. Power naturally drains from people who decline to pursue it and while he should be greeted rapturously by the faithful in Manchester, having delivered the first governing Conservative majority since 1992, David Cameron’s flame now burns less brightly than it did. We are now within sight of a post-Cameron era in Conservative politics, and already rival lamps are discreetly being lit.

Facebook Twitter Pinterest David Cameron: I won’t seek third term as prime minister

The education secretary, Nicky Morgan, broke cover first, declaring in a Spectator interview that there should be a woman in the race to succeed Cameron and it could be her. (The somewhat ageist consensus at Westminster is that by 2020, Theresa May’s time may have passed).

Morgan has suffered from living in the shadow of Michael Gove, but she’s arguably a much more interesting politician than she’s so far had a chance to show. But the reason she’s been quick out of the traps is that as relatively new MP she has a lot of ground to catch up. Right now, the moths are mainly fluttering around George Osborne.

The chancellor’s speech on Monday will inevitably be seen as a chance to set out his prospective stall (which is precisely why it will be unwaveringly loyal to the prime minister). But it’s more significant than that. Whether or not he ends up leader, it’s Osborne who will now shape Tory prospects for 2020.

Nicky Morgan considers standing for Tory leader when Cameron quits Read more

He holds the keys both to a European referendum campaign that could make or break the government (he’s widely expected to be both chief campaign strategist and also a leading negotiator of the EU reforms Cameron needs to secure) but also of a spending review that dramatically recasts the role of the state. In moth terms, that’s some flame.

Talk to left-leaning NGOs, policy wonks, lobbyists and people in local government – people wanting a Labour victory, or representing those who need one – and there’s a glum acceptance that the cavalry is not coming over the hill. They can’t just fight a guerrilla war against cuts, hoping to hold the pass until Labour gets back in, when that might be a decade away; they’ll have to engage with power where it lies now and that means with Osborne.

Submissions to the spending review are now being tailored to appeal to the chancellor’s personal ambitions, arguing that if he doesn’t spare X or fund Y then whoever’s in charge by 2020 (hint, hint) will pay the price. He will increasingly be pushed to choose between his self-imposed political mission – slashing police budgets, stripping millions from school funding, running a surplus come hell or high water – and his own personal prospects. This week may offer some insight into how he expects to reconcile the two.

One clue lies in a Tory fringe agenda speckled with debates on low pay, job insecurity and rebalancing the economy. The chancellor has developed a voracious and suspiciously sudden interest in a range of newly populist leftwing causes and while Labour might scoff at his audacity, it shouldn’t underestimate the strategic threat.

Facebook Twitter Pinterest ‘Osborne’s big problem, of course, is that his fingerprints are all over everything the government has done – or not done.’ Photograph: Anadolu Agency/Getty Images

The aim is to squeeze them to the margins of debate by occupying what some see as a new centre ground. The Osborne camp has taken the Labour leadership campaign seriously because it’s fascinated not by Corbyn but by the thing that brought him to power; a slow-burning anger against banks and corporate tax-dodgers, obscenely high pay and flatlining ordinary salaries, and politicians who just don’t get it. You don’t have to feel that anger viscerally to see where it might lead.

Osborne’s big problem, of course, is that his fingerprints are all over everything the government has done – or not done – to tackle these problems over the last five years, let alone over the next five. And that’s not the only factor limiting his prospects of promotion He’s almost as exposed as Cameron is to fallout from the EU referendum gamble. (Heads we quit the EU, and government heads will have to roll; tails we stay, triggering Tory civil war).

He will have noted, too, that it’s risky to start as favourite in a contest when the trend is for insurgents representing a break from the past. There could easily be new rising stars by 2025. And even if there aren’t, Boris Johnson remains a formidable threat as the candidate most likely to persuade non-Tory voters to switch.

But if the very idea of the austerity chancellor moving next door enrages Labour, they should be careful what they wish for. The Labour party has much to fear from his leadership, but one thing to welcome, which is that voters don’t like him much.

It’s no accident that of the two Tory modernisers who could have succeeded Michael Howard, it was Cameron – not more senior, nor more brilliant, perhaps not even the one Howard originally had in mind – and not Osborne who ran. Cameron was and is more popular than his party, the acceptable face of the brand; Osborne was and is seen as colder, more ruthless, personifying swing voters’ worst fears about the Tories.

The Tory poll lead might be smaller now if voters were being asked to choose between Osborne and Corbyn, not Cameron and Corbyn, and the chancellor is self-aware enough to know that. It’s still unclear whether he is dead set on the job or content to be the power behind another throne.

But then at this stage, the moths don’t necessarily need to know. Right now, they’re just doing what moths do; flapping blindly in circles, searching always for the next point of light.

• The headline of this article was amended on 2 October 2015 to correct a leaching/leeching homophone.

