The strains between Government allies New Zealand First and the Greens further intensified last night, as MPs from both sides lobbed grenades into each other's camps.
The latest skirmish is over the so-called waka-Jumping legislation – the repealing of which passed its first reading in the House last night.
NZ First leader Winston Peters told the Herald the Greens have not kept their word and are betraying Labour.
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"What an appalling apology that is – I'm saying to James Shaw: 'you're better than that'."
But, Shaw – the Greens' co-leader – said his party's hands are clean and he was under no obligations to vote against the law's repealing.
The Greens had begrudgingly supported making the bill into law two years ago, but made it clear they were not happy to do it.
But they were bound to it, because of their supply and confidence deal with Labour which made it clear the bill had to be supported by all three governing parties.
Speaking to RNZ this morning, Shaw said his party was obligated to support the bill – as per their agreement – but there was nothing in that agreement that said they were not allowed to support its repealing.
The bill – officially called the Electoral Integrity Amendment Bill – requires MPs who quit, or are expelled from a party, to leave Parliament more or less on the spot, instead of joining, or forming new parties.
In the past, the Greens have called this "undemocratic".
And in the House last night, they voted with National to have the law scrapped.
"We have learned that it is the letter of the agreement, rather than the spirit of the agreement, that's what counts when it comes to New Zealand First," Shaw told RNZ.
On a number of occasions – including the canning of a capital gains tax and the blocking of Auckland light rail this term – NZ First have withheld their support, as they were not in the coalition agreement.
"When it comes to the repeal of the party hopping bill, I would say we have observed exactly the letter of our agreement," Shaw said.
Asked if he was playing the same political games as Peters, Shaw said: "I learn from the master".
Peters, however, was not impressed with Shaw's logic.
"That's the defence of someone who hasn't got his thoughts or planning together when he did the arrangement in the first place.
"Now he's blaming his shortcomings on someone who did have his thoughts together; that's why we got the agreement in the letter of the law."
Peters also had Green MP Chlöe Swarbrick, who spoke on behalf of her party in the House last night, in his sights.
"The Greens will honour our 20-year position on voting on this legislation," she said.
Peters said her speech was a "terrible shame of unprincipled, apologetic behaviour".
"She couldn't tell you why she was doing it, could she?"
Meanwhile, when asked to describe his relationship with the Greens, Peters said it has been great to work with Shaw.
But he opened fire on Shaw's party.
"I have always been so sympathetic to the plight he has had, of having to operate in a party like that.
"James has got a rough idea of how it should be – but he's always apologising for how his colleagues behave and it's sad."
Peters also took aim at the Greens' ability to negotiate, citing their confidence and supply agreement with Labour.
He said the Greens didn't get as much from Labour as his party did – for example, NZ First got the $3 billion Provincial Growth Fund.
"They would hate to say this, but they should have hired me to negotiate for them as well."