Green Party co-leader James Shaw said the rules had "limited the Government's scope for change."

The Green Party is ditching its commitment to the restrictive Budget Responsibility Rules, which set targets for lowering government debt and spending.

The Greens first signed up to the rules ahead of the 2017 election while teaming up with Labour.

Labour retained a commitment to the rules, while signalling it wanted to somewhat loosen them next term.

The most stringent rules include a commitment to reduce net core Crown debt to less than 20 per cent of GDP within five years, and to keep government spending at or below 30 per cent of GDP.

These rules have caused serious upset within the Green Party base and caucus, with both female co-leadership candidates committing to get rid of them during the 2018 leadership race.

CAMERON BURNELL and KEVIN STENT/STUFF Green candidates talk about why Governments should spend more, and take part in a lightning round of questions.

The rules went out for review earlier this year and the party's policy group has now decided to scrap them, replacing them with a new economic policy that promotes greater public spending.

An email was sent to members announcing this change on Tuesday morning.

Green Party co-leader James Shaw said the rules had "limited the Government's scope for change".

"Especially in light of what we know now about the infrastructure deficit, but also because of the changing economic conditions and opportunities, we require a new approach," Shaw said.

"The arbitrary debt and spending targets, are not appropriate and have limited the Government's scope for change.

"Our new policy reaffirms our commitment to moving beyond GDP, focusing on wellbeing, and building a strong public sector. Next year we'll be developing this further and putting it in front of New Zealanders as a clear set of fiscal plans that build on environmental, social and economic sustainability."

Shaw, who is also the associate minister of finance, is understood to have been one of the driving forces behind the rules in caucus - seeing them as necessary to making the Greens more electable.

But the anger from the membership towards the rules has been palpable, and outgoing Green MP Gareth Hughes told Stuff recently that the Government had not been "transformational".

The party's review of the rules said they embedded neoliberalism and that fiscal strategy should "maintain macroeconomic stability, including full employment and controlled inflation".

"We are a party that believes in bold, progressive economic policies that focus on the health of our planet and the well-being of our people."

A number of economists and commentators have also said the rules are too stringent, suggesting the Government take advantage of low interest rates to make long-term investments.

Finance Minister Grant Robertson has announced the Government is bringing forward several infrastructure investments but it is not yet clear whether this investment will break through the rules yet.