The Green Party is unhappy with the Government's reversal of entrenching part of the Three Waters legislation.
It comes after National Party leader Christopher Luxon on Wednesday called for the Prime Minister to sack Local Government Minister Nanaia Mahuta, claiming she defied Cabinet during the vote for entrenchment - something the Greens had been pushing for.
Entrenching part of the legislation, which was labelled "constitutionally objectionable" by law experts, would've meant water assets couldn't be privatised unless 60 percent of MPs agreed to repeal the clause - as opposed to the usual straight majority.
After widespread backlash, the Government on Tuesday removed the clause.
Speaking to AM Early on Thursday, Greens co-leader James Shaw explained why his party was in favour of entrenchment.
"We proposed, and have proposed for some time that water, essentially, is a constitutional-level matter and, therefore, entrenchment would be appropriate," he told host Nicky Styris.
He added the National and ACT parties had, in the past, "got a bit of a penchant for selling off the family silver".
National, however, has said asset sales weren't on its agenda.
"We want these assets returned and to stay in local ownership and control," Luxon told AM this week.
Luxon said the only people talking about privatisation were Labour and the Greens.
ACT Party leader David Seymour, meanwhile, said last week the privatisation accusations were "nonsense".
"The Greens and Labour have been grossly irresponsible, not realising what they are doing to New Zealand's constitutional framework while trying to fight the imaginary bogeyman of privatisation," he said. "This time they have been caught out. They can't try and hoodwink New Zealand again."
Despite calls for Mahuta's sacking, Prime Minister Jacinda Ardern on Wednesday stood by the embattled minister.
