Winston Peters has accused the Greens of "misusing Labour" by supporting New Zealand First's 'waka-jumping' legislation in 2018 as one of the three governing parties - and then voting for a law change to repeal.
The Electoral (Integrity) Amendment Bill, also known as the 'waka jumping' Bill, was passed into law in September 2018. Introducing and passing the legislation is part of Labour and New Zealand First's coalition agreement.
It passed with begrudging support from the Green Party despite speaking out against similar legislation in the early 2000s.
National MP David Carter introduced a Members' Bill in October 2018 that would reverse the legislation, and on Wednesday evening it passed its first reading in Parliament - with support from the Greens.
Peters, leader of New Zealand First, slammed the Greens on Wednesday night, describing them as "untrustworthy" because they supported the legislation to pass and then contributed towards it being repealed.
Green Party co-leader James Shaw defended the party on Thursday, saying the Greens agreed to pass the legislation as part of its confidence and supply agreement with Labour.
But Shaw said the agreement didn't say the Greens had to do anything else.
"If you read the New Zealand First coalition agreement, what it says is to enter and pass a party-hopping Bill into Parliament. We did that. It didn't say anything else, and I'm told words matter," he told reporters.
Shaw insisted it had nothing to do with New Zealand First railroading Auckland light rail - a project the Government put on hold because consensus couldn't be reached with New Zealand First.
The proposal to build light rail from Auckland CBD to the airport is set out in the confidence and supply agreement between Labour and the Greens.
Shaw said, "It's because we've had a longstanding position against this kind of legislation - it goes back 20 years".
Peters said the Greens misused Labour.
"The public believe that when politicians get into Parliament they should keep their word and if they're with Labour they should stay with Labour. They should not misuse Labour or anybody else," he told reporters.
He said New Zealand First introduced the 'waka-jumping' legislation to save the Greens.
"You know how discoordinate they are. The internal scrapping in the Greens knows no bounds... You go back on your word - that's instability."
Carter has thanked the Greens for supporting his legislation.
"I'd like to thank the Greens for voting for this legislation. They have reasserted their values as a party that stands up for free speech, and we look forward to working with them further to make sure this Member's Bill passes," he said.
"No credible democracy should ever have given the power to party leaders to dismiss elected Members of Parliament because they don't agree with the leader.
"It is an affront to democracy. The public expects elected members to advocate strongly without fear of being punished by their Leaders for expressing different views."
Peter also spoke out against Labour's pursuit of a law change to help commercial rent disputes.
Justice Minister Andrew Little said on Thursday the law change would not go ahead because consensus could not be reached with New Zealand First - but $40 million is still being allocated to assist disputes.
Little announced in June a temporary change to the Property Law Act to ensure businesses suffering as a result of the COVID-19 response would get help to resolve disputes over rent costs - but Peters said it's a "waste" of $42 million.
"What you're saying is you're trying to break the sanctity of commercial contracts and we said you can't do that - and now they're throwing $42 million at it," he said.
"Andrew Little knew full well that the arrangement we were working on, the Bill was so inappropriate and I told him so. I've got a commercial background and I'm not going to sit there and not use it in circumstances where the landlords and tenants of this country need a fair and consistent go."