It comes as the Deputy Prime Minister and several other politicians wait to see if they will be allowed to keep their jobs.
One question was all it took to put the future of Prime Minister Malcolm Turnbull's second-in-command in doubt, leaving Barnaby Joyce, in his words, shell-shocked.
And the fallout could endanger the traditionally close bonds between Australia and New Zealand.
The controversy started when a New Zealand Labour Party MP asked his parliament if a child born in Australia to a New Zealand father were automatically a New Zealand citizen.
Ultimately, New Zealand prime minister Bill English confirmed Mr Joyce was, unwittingly or not, a New Zealand citizen.
Foreign Minister Julie Bishop has now sharply criticised New Zealand Labour, saying the matter could affect the two governments' relationship if it wins the next election.
And Ms Bishop has accused Opposition Leader Bill Shorten of colluding with the Australian Labor Party's trans-Tasman counterparts.
"Bill Shorten has serious questions to answer. This is highly unethical, at least, but, more importantly, puts at risk the relationship between the Australian government and the New Zealand government. Bill Shorten must reveal who he put up to this dirty task and the details of his urging of a foreign political party to be involved in efforts to undermine the Australian government."
New Zealand Labour Party leader Jacinda Ardern admits she cannot explain why MP Chris Hipkins decided to air the question in parliament.
She says the question originally came from a member of Australia's Labor Party.
But New Zealand internal-affairs minister Peter Dunne says the decision to investigate Mr Joyce's citizenship was initiated by inquiries from journalists.
In Australia, choosing to put the spotlight on the Opposition, the Coalition has indicated it will refer the cases of five Labor MPs to the High Court as well.
Labor has denied there are any issues with its MPs.
Labor MP Richard Marles has told the ABC the Government is resorting to desperate and damaging tactics.
"There are no two countries in the world that are closer than Australia and New Zealand. A foundation of this relationship is that it has to be above partisan politics. And in the desperation in which they are dealing with the Barnaby Joyce affair, you've now seen Julie Bishop go out and trash the foundations of that relationship by saying it is partisan."
The fact the Nationals leader is a New Zealand citizen by descent potentially makes him ineligible to sit in Australia's parliament.
The Government has said it is confident it will win a High Court case to allow Mr Joyce to keep his Cabinet position.
But Greens leader Richard Di Natale is calling on him to follow in the footsteps of two Greens senators who resigned after finding out they held dual citizenship.
Dr Di Natale says he hopes there are no more citizenship surprises to come.
"We're entering constitutional-crisis territory here. We need to have this matter resolved, and the way to have it resolved is to appoint an independent auditor where there are questions over Members of Parliament, they be referred to the High Court. At the moment, each individual case is dribbling out. We're relying on the good work of our friends in the media and, indeed, people who are prepared to hold Members of Parliament to account."
If the High Court ruled Barnaby Joyce ineligible for parliament and a by-election in his seat were lost, the Government would need a crossbencher's support to stay in power.
