"I'm getting text messages from journalists because I think one of major parties is trying to say I'm a British citizen by virtue of my father".
Mr Xenophon, whose Nick Xenophon Team controls three seats in the Senate, has spent the past week denying any dual citizenship concerns despite having a Greek mother and a Cypriot father.
Along with Mr Joyce and Senator Matt Canavan, she is the third Nationals MP to face a High Court battle over dual citizenship.
Australian Prime Minister Malcolm Turnbull convened an urgent cabinet meeting just after 6pm, where it was decided, based on advice from the Solicitor-General, that Nash did not have to resign from either the Senate, or lose her cabinet spot as minister for rural health.
"On the basis of the Solicitor General's advice, the Prime Minister has indicated to me he sees no reason for me to stand aside from my (portfolios)", she said.
In circumstances that remain murky, this reactionary measure, which could disqualify millions of people who were born overseas or had a parent or grandparent born overseas, was first invoked against two Greens senators.
The obscure rule was little known until recently but it has major implications for Prime Minister Malcolm Turnbull's Liberal-National coalition government, which hold a slim one-seat majority in Parliament's lower house.
Australia's constitution bars citizens of another country from standing for parliament, and there have been several resignations because of that in recent weeks.
"Senator Nash's statement means the entire National Party leadership is now facing disqualification from the Parliament", she said.
There are the two resigned Greens senators, Scott Ludlam and Larissa Waters.
Xenophon, who just three days ago joked with Senate colleague Sam Dastyari that he was not a Greek citizen, confirmed he was getting advice as to whether he may be a United Kingdom citizen by descent.
This led to Australian Foreign Minister Julie Bishop claiming she would find it hard to build trust with a New Zealand Labour-led government.
While the High Court will begin considering the status of Mr Joyce and Senator Canavan next Thursday, the government will not be able to refer Senator Nash to the court until September when Parliament next sits, leaving her eligibility in doubt.
Nash's case illustrates how far section 44 (i) can reach.
Australian Conservatives senator Cory Bernardi has suggested suspending the Parliament.