Former MP Peter Dunne has blamed the Government's recent woes on Winston Peters getting a taste of the power while Prime Minister Jacinda Ardern was on maternity leave.
The veteran ex-United Future leader told The AM Show on Monday Mr Peters was "emboldened" by his six weeks in the top job.
"When he was Acting Prime Minister while she was on maternity leave, he did a reasonable job. In a way that's emboldened him and I think the contrast between the relatively calm times during her absence and the chaos that's occurred since, is pretty stark - and he's playing to that."
Since coming back from maternity leave, Ms Ardern has had to deal with accusations of physical violence against one of her ministers, and the resignation of another.
Mr Peters has also publicly disagreed with Government ministers on issues like the refugee quota.
"We've had pretty good evidence over the last few weeks just how deep the divisions are, the fact that all policy now effectively rests on New Zealand First," said Mr Dunne. "It's not a Labour-led Government - it's a New Zealand First-led Government, even though they've only got 7 percent of the vote."
His comments come after a carefully stage-managed event in Auckland on Sunday, where Mr Peters and Ms Ardern spoke of a "unified" coalition and answered vetted questions.
Mr Dunne called it a "sort-of kumbaya stage session", while National leader Simon Bridges said it was a "Trump-like attempt to avoid tough questions with a stage-managed pep rally and carefully vetted questions".
The US President is known for rarely taking questions from the media his team hasn't vetted in advance. According to the Washington Post, as of Monday it had been 577 days since he last did so.
"What we've got sort of 10, 11 months, nearly a year in, is platitudes, when there are real issues that are hurting New Zealanders," Mr Bridges told The AM Show.
"There's an economic downturn - and let me just get this one in, it's really important - is cost of living right at the moment is going up higher than wages."
Mr Bridges is convinced there is a different agreement governing the coalition's goals than the 12-point priority plan released at Sunday's event.
"This is not a conspiracy theory or anything the like - Winston Peters and Jacinda Ardern have confirmed there is another, secret document," he said.
"It's locked in some safe. It actually does have what's really going on here and the horse-trading… It'll be what Winston Peters wants to achieve. It's probably in a way what we're seeing happen."
Mr Dunne said if Mr Peters doesn't get his way, he'll "pull the pin" and take down the Government.
"He's done it before and he'll do it again. [Ms Ardern's] not prepared to risk that, and consequently she's his hostage."