Reasoning is as simple as it is heroic: PM Tony Abbott. Photo: Alex Ellinghausen
This budget is about two deficits - the fiscal one Joe Hockey and Tony Abbott inherited, and the political one they seem rather too relaxed about creating.
The clear danger is that in their hairy-chested enthusiasm to address the fiscal challenge, adopting deeply unpopular measures designed to get the balance sheet back into shape, they forget about the political authority needed not just for that effort but in order to keep on governing.
Big reform tasks lay ahead in areas such as tax and industrial relations - both of which have been put on the "to-do" list for a second term. Such reforms will take courage and they will take authority.
As the Fairfax ReachTel poll reveals, support for the Coalition has already tanked - not to irrecoverable levels perhaps, but who knows how long-lasting it is? And this is before the budget has even been tabled and, presumably, ahead of all of its nasties being revealed.
Coalition MPs and their supporters are rightly worried as they watch their government spend its modest reserves of political capital up front, and then some.
One finding is particularly instructive: that voters are relaxed about the deficit tax. It raises the possibility that they accept the policy but continue to mark down the government for the broken promise.
Abbott's reasoning is as simple as it is heroic. In order to deliver on his vision for Australia, harsh, drastic measures are required. He even predicted at one point that voters would thank the government down the track.
Yet the course he has chosen is so unambiguously not the one he sought the voters' approval for, and that fact is eroding his standing.
If his deficit tax, pension cuts, Medicare co-payments, and petrol excise increases were merely unpopular that would make for difficult politics. But 24 months out from an election, and facing complex problems, such an approach might well be eminently justifiable.
His problem, however, is that for the most part, these measures represent specific broken promises.
Ultimately, it might be easier to repay $123 billion of accumulated deficits over the next four years, then retrieve the confidence of weary voters.