Over the past five years the biggest question in British politics has been this: how might George Osborne’s cuts be stopped? In a decade that will be defined by austerity, this remains the problem that underpins all the others in our politics. Suddenly, we’ve been given a possible answer.

Many lessons can be drawn from the debacle over cuts to tax credits, and the remarkable past fortnight – in which the Sun took up arms against the party it helped create, in which a desperate mother shouted “shame on you” at the Tory she’d voted into government, and the habitually sedated House of Lords stumbled into rebellion.

It’s not that Osborne, the tactician’s tactician, has made a rare misstep – or any of the other conclusions reached by our cabal of over-sophisticated and under-attentive political commentators. What we’re seeing is that, after half a decade, the chancellor is finally reaching the point at which his cuts have to go so deep and so wide that they can no longer be denied or plausibly defended. The irresistible force of implementing year upon year of austerity means the Conservatives have to start hurting and offending their own supporters. This is the point where Osborne’s maths finally outruns his politics.

Much bigger cracks will be revealed in three weeks’ time, when the chancellor details in his spending review how he’ll squeeze another five years of savings from the public sector. And just as happened with tax credits, the government will present a series of large cuts as if they are simple and almost inevitable – only to find that some will trigger an all-out war.

To understand why, look closely at what happened with the tax credit cuts. Go to June 2010, when Osborne announced in his first budget that working tax credits and child tax credits would be cut for middle-class families. The coalition managed that without too much outrage. When, going into the last general election, the Tories vowed to hack another £12bn from social security, even while protecting pensioners, it became almost certain that working tax credits would be cut again. The chancellor doubtless thought he could drink from the same well twice – especially if he promised a higher minimum wage. There was just one problem: this time around, he would be snatching money from working-class families who relied on that subsidy to stay employed.

This makes the past month’s rows both inevitable and politically utterly stupid. In order to make savings worth a mere 0.5% of all public spending, Osborne decisively broke his longstanding pledges to voters. When he and David Cameron began making cuts in 2010, they made two explicit promises. First, austerity would barely be noticeable – it would work by stripping the fat from a wasteful and overpaid public sector. Second, where cuts were to be felt, ministers promised it would be the “skivers” who suffered, not the “strivers”.

Now, by taking £4.4bn off the working tax credit, the chancellor was not only making a very obvious and painful cut – he was punishing exactly the kind of hardworking families all parties claim to support. A graphic in the Financial Times last week made the point with painful precision: your typical bank clerk with two kids stood to lose £2,262 a year; a dental nurse £2,027; an administrator in local government £2,304. A roll call of all the strivers to be made poorer by their supposed protectors.

One presumes Osborne didn’t do this out of foolishness or brute evil, but because he had nowhere else to go. In his first five years, the chancellor precisely targeted his benefit cuts, hitting small groups of the population who had little representation in politics or the media – such as people with disabilities. That is no longer the case. Now the chancellor’s only options on cutting welfare necessitate breaking promises: either by taking money off pensioners, or by U-turning on plans to cut welfare – or by walloping “striving” families again and again, through tax credits and housing benefit.

The same goes for this month’s spending review, where the chancellor has to make another £11bn worth of savings. Again, he is boxed in by a whole series of iron-clad promises, with spending on healthcare and aid and schools and defence all ringfenced. Just like the working tax credit, he’ll have to go back to the areas walloped in the first phase of austerity – only this time the comeback is likely to be much worse.

Take local councils, one of the big losers between 2010 and 2015 and set to lose again. As Gary Porter, Conservative chair of the Local Government Association argues, local councils like his own have already made all the back-office savings they can. What’s left to cut now are the basics, the things council-tax payers will notice: bin collection, street cleaning, the maintenance of parks. Since the government has promised to pump more money into infrastructure, we’re set for a kind of public policy farce in which Whitehall ministers line up for photo ops in hard hats and hi-vis while the potholes multiply across high streets.

Or look at prisons, which as part of the ministry of justice have come under huge pressure in the past five years and are in for more. Already prisons are turning into increasingly-violent warehouses for youngish men, with officer numbers plummeting while prisoner assaults and suicides are hitting record highs. Twenty-five years on from Strangeways, prison officers are reporting fresh outbreaks of rioting.

Voters won’t necessarily get upset over prison conditions, and they’re more likely to blame their council for rubbish on the streets. But the political risk is that the public is left with a lingering sense of public disorder. The government will cop it if the NHS or social care go into meltdown – and there too alarm bells are ringing.

Ministers lived up to their promise to protect health spending between 2010 and 2015 – but only just. Government funding of the NHS rose by below 1% a year (after inflation) during Cameron’s first five years – the lowest level since the second world war. The health service now routinely misses targets on A&E waiting times, on waiting for cancer treatment, or on diagnostic treatment.

Will all of this automatically produce a crisis? Not necessarily. Politics is more than just a poorly written algorithm in which X produces Y, and the Tories can still out-PR their critics. But over the next five years, austerity will produce many more episodes like the war over tax credits. And it will damage the Tories’ standing with voters more than the Labour opposition or the trade unions. Here’s my bet: if anything is to stop George Osborne, it will be Osbornomics.