The row over Barnaby Joyce's citizenship is threatening not only the Turnbull government, but Australia's relations with New Zealand.
And as the trans-Tasman spat continues to simmer, the Australian Labor Party staffer who fished for information about New Zealand citizenship has been identified.
Prime Minister Malcolm Turnbull and Foreign Minister Julie Bishop sought to turn the tables on Bill Shorten on Tuesday, accusing the Labor leader of treachery and international conspiracy.
The High Court has been asked to rule whether Mr Joyce's NZ citizenship by descent, which he has now renounced, made him ineligible for election to the Australian parliament.
The coalition blames Mr Shorten for tipping off the NZ government, via NZ Labour MP Chris Hipkins, about the deputy prime minister's potential citizen status.
Labor senator Penny Wong's chief of staff Marcus Ganley, who is from New Zealand, spoke to Mr Hipkins about citizenship law in recent weeks but did not mention Mr Joyce.
Mr Hipkins subsequently asked questions about Australia-New Zealand citizenship laws in the New Zealand Parliament.
There was no specific reference in the question to Mr Joyce, nor was Mr Hipkins aware of any issue relating to the Australian deputy prime minister.
The NZ minister Peter Dunne said any suggestion Mr Hipkins instigated the issue was"utter nonsense".
"They were not the instigator. Australian media inquiries were," Mr Dunne tweeted.
That did not stop the prime minister and Ms Bishop ramping up their attack on Mr Shorten.
"He chose to plot with his Labour Party comrades across the ditch," Mr Turnbull told parliament.
Mr Shorten told caucus colleagues the government was engaging in conspiracy theories.
"The Turnbull government is in a constitutional crisis caused by its own negligence," Mr Shorten said.
"The deputy prime minister, who I suppose we should now call the foreign minister or the leader of the 'dual Nationals' is unwittingly or not a dual citizen."
With NZ heading to an election in September, Ms Bishop told reporters it would now be "very difficult to build trust" with an NZ Labour government.
NZ Labour leader Jacinda Ardern met with the Australian high commissioner on Tuesday to clarify Ms Bishop's statement.
"I'm disappointed she's expressed her view in that way ... but I will not let that get in the way of our relationship," she said.
Ms Ardern said she and her party had no knowledge of the issues around Mr Joyce until they broke in the media on Monday afternoon, but she acknowledged her MP should never have asked the question.
Labor foreign affairs spokeswoman Penny Wong said Australia's long friendship with NZ deserved better than a "cheap attack by a government under pressure".
Adding to the pressure are concerns a by-election in Mr Joyce's seat of New England could take the one-seat majority government into a minority position.
However, crossbenchers Cathy McGowan and Rebekha Sharkie said they would continue to support the government on questions of supply and confidence.
