It has always been the case that the Coalition would be judged on the effectiveness of their economic policies. The salvation of the economy from the phantom menace of "becoming Greece" has, after all, been the explicitly stated reason for this Faustian pact.
It is, therefore, particularly bad news that on Wednesday a paper from the top economists at the IMF was published  suggesting what many already knew: that a path of unbalanced, overly zealous austerity has a much more disastrous effect on economic growth than originally envisaged.
Olivier Blanchard, the IMF's Economic Counsellor, and its chief research economist Daniel Leigh, have confirmed, complete with scatter diagrams, what was trailed in October's World Economic Outlook report . Specifically, that a cut of government spending results in, not, as previously thought, an equivalent loss in economic output, but triple that.
Oops! We got our multipliers radically wrong, folks. Sorry, Greece. Sorry, Europe. Sorry, World. Everyone makes mistakes, you may say.
But this was not an error of scientific judgment. It was an error of ideology, policy and presentation. The Coalition was caught in a pincer movement. The rhetoric of doom and gloom was essential to defeating any opposition to a programme of ideologically driven cuts – and making everyone who argued against it look like a debt denier. Its unfortunate, but completely foreseeable side-effect however, was to scare the private sector stiff. The slack that was being created at a phenomenal rate, was not being picked up by private enterprise.
In other words, if you want someone else to take over the wheel, it really doesn't help to be running around screaming "we're all going to die". The net result has been to terrify the private sector into reserve hoarding and balance sheet retrenchment. The blame for that lays entirely with the Coalition and any other government that chose to speak the grand guignol language of fear.
"Forecasters significantly underestimated the increase in unemployment and the decline in domestic demand associated with fiscal consolidation", Blanchard and Leigh conclude, causing one commentator to describe the paper  as "a mea culpa submerged in a deep pool of calculus and regression analysis".
Increasingly, then, our Chancellor refusing to admit error and put into effect a "plan B", cuts an isolated figure. This will only encourage the dissenting voices in Opposition – whose catchphrase "too far, too fast" could have been the title of this latest IMF paper. It will also encourage dissenting voices within his own party, who have shown open resentment for the coalition deal.
And increasingly, the hollow excuses of too much rain/too much sun/not enough sun/three flakes of snow more than expected/the Royal Jubilee/the Olympics/the dog ate my homework, will start to sound like precisely that: hollow excuses.
If, as some predict , we slide into a triple dip recession, the wider public will begin to perceive that, far from "healing", the economy is choking with an occasional gasp for breath. And George Osborne will look increasingly incompetent and devoid of allies, under a PM who showed through the Mitchell affair that loyalty in not a favourite currency.
Osborne's peculiar brand of neoliberal auto-erotic asphyxiation has limits. The safe word for stopping it is "reshuffle".