Former cabinet minister Judith Collins says NZ First leader Winston Peters owes voters an explanation - were the coalition negotiations genuine, or a fraud?
Mr Peters negotiated with National and Labour after the election, and decided to form a government with Labour.
But it's now known that a day before the election he initiated legal action against senior national party MPs, including former prime minister Bill English, over the leaked details of his pension payments.
That has raised questions about whether he ever intended supporting a National-led government.
Newshub's AM Show host Duncan Garner put it to Ms Collins on Friday: was the process a fraud?
Ms Collins replied: "It does now look a bit like that, doesn't it. Certainly at the time we were very much convinced on our side that there were genuine negotiations going on, but I've got to say it's not looking like it was quite so genuine any more."
Ms Collins said Mr Peters should front up.
"I think New Zealanders are owed an explanation - was he being genuine?"
Mr Peters' legal action also attempts to gain access to the communications records of two journalists who received the leaked information about him.
That has prompted warnings from media freedom advocates who say it could have a chilling effect.
"When a politician starts placing his hands on what should be confidential phone records, confidential notes and recordings and so on, our ability to hold power to account ... is compromised," Commonwealth Press Union former chair Gavin Ellis told Radio NZ.
ACT Party leader David Seymour says it's completely unacceptable.
"Journalism is part of a free society, a free media is a pillar of a free society and journalists have rights and privileges," he said.
Mr Peters is refusing to discuss the legal action, saying it's sub judice.
That's also being questioned.
Christchurch law professor Ursula Cheer says it's a civil case which is highly unlikely to go to a jury trial.
"In theory he can (talk about it) but he would have to be careful in case it was argued he was trying to advance his case," she said.
But Ms Cheer says the issue can still be raised and discussed in parliament.
"The Privileges Act gives protection ... the act covers any form of statement made in parliament that might breach criminal law or any other sort of law."