Claire Trevett: Labour and the Greens' fiscal Kumbaya while PM Bill English corrals cats

Happy, happy, joy joy - as long as it's within budget. Green Party co-leader James Shaw (left) and Labour Party finance spokesperson Grant Robertson. Photo / Jason Oxenham

When Labour's Finance Spokesman Grant Robertson was preparing his speech on the new 'Budget Responsibility Rules' between Labour and the Greens, he was pondering including a wee Adele joke.

It was a quip about the lyric "hello from the other side" and was intended as a reference to the perceived chasm between Labour and the Greens and the business audience he was speaking to.

The speech and the two-page list of 'rules' amount to a public declaration Labour and the Greens will not fritter away the family fortune - or at least there will be self-flagellation and hair shirts if they do.

It was the next phase of Labour's Operation Ready to Govern - intended to try to voters Labour could be trusted with the purse strings - and, more importantly, stop the Greens mounting a shock and awe offensive on the Treasury vaults as well.

Whether it works remains to be seen. Among the initial reaction was some disgust from supporters of the left, including the Council of Trade Unions which questioned whether Labour would be able to meet the 'investment' required within its rules.

One Twitter user argued Apple would not try to sell its next iPhone as a budget household item instead of a premium product - and neither should Labour-Greens with their policies.

Nonetheless, the paper recognises that in order to be able to manage the books, you have to get control of the books first.

Labour and the Greens both recognised the perception National was better at the books than Labour. Add the Greens in as well and the alarm bells were deafening.

That is not just because the Greens like an expensive policy or two. It is because of their potential power if in Government.

For the last eight years, the Government's support parties have been minuscule - sometimes noisy but without that much power.

On current polling, the Greens are set to be at least one third the size of Labour.

Shaw recognised as much when he said it had been some time since a "medium-sized" party was in government and the public needed to know how it would handle that power.

The troubles of National over Resource Management Act reforms illustrate the problems when it comes to even small support partners.

On Wednesday there was the spectacle of two of National's support partners - Act and United Future leaders David Seymour and Peter Dunne - standing side by side to set out their counter-offer on the Resource Management Act reforms.

It had a distinct hue of school children scrapping to get the teacher's attention.

Two hours later, the Maori Party put out a press release announcing it had reached agreement with National and would support the RMA.

Its support has come in return for the Government concessions on greater iwi participation in consent decisions and scrapping proposed ministerial powers to override local councils on the issue of genetically-engineered crops.

National has been talking about the RMA reforms since 2009. Since then they have been put on and off ice more often than Dan Carter's knee.

There was a glimpse of light after the 2014 election when National could have ploughed ahead with support of just one of either Dunne or Seymour.

NZ First leader Winston Peters' win in the Northland byelection meant National was an MP down - and needed two votes from support partners instead of just one to pass legislation.

The Maori Party put on a rather impressive show of outflanking its support siblings.

Whether they will be congratulated for it is another matter.

The deal on the reforms is not free of political risk for either National or the Maori Party.

For National there was already disquiet about the extent to which iwi would have a say under the reforms.

There is a risk of a backlash from conservative, business and rural voters because of the greater heft it gives to Maori and iwi in decisions on consents.

The likes of Don Brash and Peters are already beating that drum loud and strong - and Seymour is doing little to calm it.

He was genuinely astonished that National did not want to take up the Seymour-Dunne option which would have reduced the influence of iwi and given greater recognition of property rights, saying the Maori Party had kicked National from pillar to post and National would feel the sting from their voters.

He wanted "to highlight to National voters in the heartland that their party is not doing what it says on the box."

For the Maori Party, co-leader Marama Fox took a hardball approach over the final concession on GE crops because while iwi leaders were happy with what had already been secured, it was not the iwi leaders she will have to defend the Maori Party's actions over.

She will have to go out into Maori communities, where many do not know the intricacies of the reforms, and counter the likely Labour line that the Maori Party had thrown them under a bus by signing up.

It was a quite astonishing staring down of National - and shows it does not pay to underestimate Fox.

National will be hoping nobody will contrast it with the happy joy joy kumbaya signing ceremonies on the Labour-Greens side of things.

What will terrify National is that the negotiations illustrated the near impossibility of getting all three of its support partners to agree on anything.

That could be dangerous for effective government if, after 2017, it needs all three to pass legislation. Until now it has been able to pick and choose.

The prospect of having to find common ground between Act, United Future and the Maori Party on every measure should be enough to send English to animal training school for a lesson on corralling cats.

It's enough to make the medium-sized NZ First look a lot more attractive.