Nick Xenophon will let the High Court decide his fate if it is confirmed he is a dual citizen, with the key Senate crossbencher determined to dig in and not resign from the Senate.
Senator Xenophon is urgently seeking clarification from the British Home Office over his citizenship status after questions were raised about his father's nationality.
Theo Xenophou was born in Cyprus, which remained a British colony until 1960. He migrated to Australia in 1950, where Senator Xenophon was born. Travel documents show Theo came to Australia on a British passport.
While the South Australian senator has renounced Greek citizenship, which he automatically received from his mother, he was not aware he held possible British citizenship until a journalist contacted him "a few days ago".
"All I can do is check and release whatever I get," he said.
"Whatever happens, happens.
"We are trying to get some further information, we are trying to get some clarity. Hopefully we get it in the early hours of Saturday morning."
Senator Xenophon said if it was confirmed he had British citizenship by descent, he would not resign.
"It has to go to the High Court," he said.
"You let it go to the High Court, that is what you do. That is the appropriate thing to do, I think."
The Nationals leadership has been thrown into disarray by the constitutional crisis, with Deputy Prime Minister Barnaby Joyce and his deputy, Fiona Nash, found to have received dual citizenship by descent, at birth.
While Senator Canavan stepped down from the cabinet, Mr Joyce and Senator Nash have maintained their positions.
Attorney-General George Brandis on Friday said he regrets Senator Canavan's resignation from his ministry, which he said was done as a "precautionary step" after his story was made public.
He also defended the decision to withhold announcing Senator Nash's citizenship issues for almost a week.
The NSW senator received advice from the British Home Office on Monday she was a dual citizen through her Scottish-born father, but did not announce it to Parliament until the dying moments of the last sitting fortnight.
Senator Brandis said he and Prime Minister Malcolm Turnbull were advised on Monday night of the situation but the government wanted to wait for official confirmation.
Senator Nash received confirmation of her dual citizenship from Britain at 5.40am on Thursday, but the government did not act until the Solicitor-General's advice confirming that came through at 5pm.
An urgent sub-committee of cabinet was called, where Mr Turnbull, Senator Brandis and Foreign Minister Julie Bishop decided to refer the matter to the High Court. Senator Nash made her announcement to the Parliament just under an hour later.
The government remains confident its three MPs will be found to eligible to remain in Parliament.