This week's warning from Prime Minister Jacinda Ardern that the Budget was bare of treats was startling enough for former finance minister Steven Joyce to break from tweeting about the pesto ingredients harvested from his Albany vegetable garden.

Upon hearing Ardern say all the money would be sucked up by fixing hospitals, schools and miscellaneous business and blaming "nine years of neglect by National", Joyce wasted no time tweeting.

New Zealand's version of Cassandra the false prophet was about to be vindicated - he could almost smell his much-mocked fiscal hole finally coming to fruition.

"Ardern is talking an unmitigated pile of political tosh," he pronounced, saying he had warned repeatedly during the campaign that Labour's Budget allowances were too tight and now they were "trying to point the finger instead of admit it".

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So we enter the smog of a period of he said, she said about how bad things really are, whose fault it is and how it should be paid for.

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Jacinda Ardern has said the case of Middlemore Hospital buildings "rotting around the patients" showed the urgency of the work needed.

Finance Minister Grant Robertson cast it in household terms, saying National was so busy trying to get back to surplus that it neglected basic maintenance. He argued it was like somebody putting all their money into a savings account while their washing machine stood broken.

Robertson now says he will fix the washing machine but will not break the savings account (Labour's "fiscal responsibility rules") to do so.

Those rules stipulate it must remain in surplus and pay down debt - which are very similar to the same goals Robertson had criticised National for.

Actually, if there is a compelling enough reason to "break" a promise, it should be done.

If the public can be convinced of it, they will accept it even if somewhat begrudgingly.

There would be a hue and cry and inevitable "told you so" yelps from the likes of Joyce, but not an unsurvivable one.

In particular there is leeway for a new and popular government to go back on a promise because it usually has the political capital to withstand it.

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For a combination of those factors, Sir John Key got away with raising GST in 2010 as part of a "fiscally neutral" tax switch to pay for those income tax cuts.

Ardern is still in that sunshine, lollipops and rainbows stage of her relationship with voters.

Ardern ran on a platform of hope and change. She cannot stop after the first half.

If those fiscal rules are preventing her doing little more than tarring the ship, she needs to look at them again.

They effectively mean one promise is preventing them fulfilling other promises - not helped by the cost of the support parties' promises.

Others have made the argument for Labour to break those rules, especially given low interest rates for debt.

They include Green co-leader James Shaw who willingly signed up to the same fiscal responsibility rules with Labour before the election.

Newsroom's Bernard Hickey has suggested they treat infrastructure issues and population growth in Auckland as akin to a "shock" similar to the Christchurch Earthquake. That could then justify drawing down extra debt.

When National was confronted with that very disaster it dropped some of its own wishlist - it downsized and delayed its own tax cut programme from the 2008 campaign because of the Global Financial Crisis and Christchurch Earthquake. Instead it did the swap of a GST increase for income tax cuts in 2010.

National's approach was based on then finance minister Bill English's distinction between the "must haves" and the "nice to haves".

Those on the right, including the Act Party, are arguing that rather that abandon its rules Labour should pay for this by dropping some of its own nice-to-haves.

The chief nice-to-have they point to is the fees-free policy for tertiary level students at universities or other institutions.

Ardern does not see that as a nice-to-have, although it undoubtedly is so for at least some given it is applied universally.

But Ardern cannot back away from it now - it was a cornerstone promise of her election campaign, one of two pledges she pointed to as a stamp of her own leadership rather than a continuation of Andrew Little's.

At the behest of NZ First she has already had to drop another of those key policies – the "water tax" on commercial users, such as irrigation, to pay for water quality measures.

On the bright side, the debate has at least diverted attention away from Labour's plans to raise fuel taxes.

And within two days, Joyce was back to the issues that bedevil a Dairy Flat gardener, tweeting about the weather.