The High Court will consider whether Mr Joyce’s citizenship of New Zealand means he was invalidly elected at the last election.
The opposition is urging Mr Joyce to follow the example of his Nationals colleague Matt Canavan, who resigned his ministerial position over a similar dual citizenship case, now also before the High Court.
“There is no way that you could expect a second generation Australian such as Barnaby Joyce to have any sense that there'd be some nexus to citizenship of another nation,” Nationals senator Barry O’Sullivan said.
He said the “significant difference” in Senator Canavan’s case was that his mother took direct action to sign her son up for citizenship, albeit allegedly without her son’s knowledge.
Senior government figures – including the Prime Minister Malcolm Turnbull, Attorney General George Brandis and Barnaby Joyce himself – have expressed their confidence that the High Court will allow Mr Joyce to continue on in parliament, based on advice from the government’s lawyer.
But Senator O’Sullivan said if Mr Joyce was disqualified and forced to recontest his own seat of New England in a special by-election, he would likely win it again.
“I'd make a prediction – I'm happy to bet you a carton of XXXX beer – that Barnaby would increase his majority in New England if we had a by-election,” Senator O’Sullivan said.
“You betcha, head and shoulders.”
“All of us … talk to hundreds of constituents each week and nobody is blaming the individuals who find themselves in these plights.”
Mr Joyce told reporters outside Parliament House on Tuesday morning he was still “shell shocked” at the news.
He confirmed he would not be reigning as deputy prime minister or the agriculture minister, as it was “more likely” than not he would survive the High Court process.
“You just continue on with the work,” Mr Joyce said.
But he would not be drawn on whether he would recontest his Lower House seat if he is disqualified and New England holds a by-election.
The Turnbull Government’s one-seat majority would hinge on the results of the by-election. Former independent MP Tony Windsor, who was succeeded by Mr Joyce when he chose not to contest the 2013 election, has already indicated he would not rule out contesting the seat.
“That's hypothetical. Let's cross that bridge when it happens,” Mr Joyce said.
