Prime Minister Malcolm Turnbull has conceded there could be "consequences" for his wafer-thin hold on government if more Coalition members of the House of Representatives are found to be ineligible because of their dual citizenship.
But Mr Turnbull pushed back against a call for a constitutional change that would allow dual citizens to sit in Parliament, saying the more immediate issue was MPs being disqualified by foreign laws that granted them citizenship even if they were unaware of it.
Following Fairfax Media's revelation that backbencher John Alexander faces doubts over his eligibility, the Prime Minister said Mr Alexander had reinstated his belief that he is not a dual citizen
"If the High Court concluded there are a number of members of the House of Representatives that were not eligible to sit in the Parliament, then there would be a series of byelections. Depending on the result of the byelections, that could have consequences for the government," Mr Turnbull told ABC radio.
The government's fragile working majority in Parliament's lower house could be put at risk by the ongoing citizenship fiasco, which has already sent former deputy prime minister Barnaby Joyce to a byelection.
Mr Turnbull will meet with Opposition Leader Bill Shorten on Wednesday, after the Coalition proposed universal disclosure of MPs' citizenship documents; a transparency measure designed to end the chaos but which could end the government.
The Prime Minister defended his voluntary disclosure proposal, saying: "If you are going to be in a position where you say you do not trust anything any member of Parliament says in their disclosures, then ... you would literally be creating a huge audit office".
Mr Turnbull also pushed back against Liberal MP Craig Laundy's call for a referendum to allow MPs to be dual citizens.
"I think it's questionable whether Australians would welcome dual citizens sitting in their Parliament," Mr Turnbull said.
"Craig's raised that point. It's a fair point and, in many countries, dual citizenship - like the UK - is not a bar. But I think the more direct question is, should you be disqualified by a foreign citizenship of which you have no knowledge and which you have never accepted."
On Monday, Fairfax Media revealed Mr Alexander's father was born in the UK. The MP is now rushing to clarify his status.
The Prime Minister said Mr Alexander has "stated publicly, and this is what he said to the party, that he believes he is not a dual citizen".
"I take it as a given that every member of the House and the Senate, as of today, believes that they are eligible to sit in the house or the Senate, he said.
Any MP who knows they are a dual citizen, he said, should resign.