Coalition senator Matt Canavan is standing firm in refusing to follow Greens senators Scott Ludlam and Larissa Waters in resigning from the Senate over his dual citizenship.
The senator and former Turnbull government minister held a press conference in Rockhampton confirming he would take the case to the High Court.
Senator Canavan is seeking further legal advice but believes the fact that his mother signed him up for Italian citizenship - allegedly without his knowledge or consent - means he is not in breach of Section 44 of the Constitution.
"I was working on the presumption you would have to fill out forms, give consent and sign papers to become a citizen of another country," he said.
Section 44 makes it illegal for a dual citizen to sit in the Australian parliament.
It is the section that saw two Greens senators resign in recent weeks: Scott Ludlam, over his New Zealand citizenship; and Larissa Waters, over her Canadian citizenship.
Canavan, Waters and Ludlam all claim they were unaware of their second citizenships, but Matt Canavan has the additional claim that he has never even visited Italy.
Senator Canavan resigned from the cabinet over the revelations, handing his portfolios to the Nationals leader Barnaby Joyce.
Media coverage in the days following the resignation has been focused on whether or not it is possible that Mr Canavan's mother would have been able to register her son as an Italian citizen without at least his signature.
"My mum acted with what she thought was my best interests and had no idea of the ramifications around any of this," Senator Canavan said.
Di Natale: 'He should do the honourable thing and resign'
Greens leader Richard di Natale is calling for Senator Canavan to step down.
He said it was inconsistent for Senator Canavan to resign from the ministry but not the Senate itself.
"He should do the honourable thing and resign," he said.
"Ignorance is no excuse."
Mr di Natale says the Coalition senator should follow the lead of Greens senators Ludlam and Waters.
"For people to have faith in the system, people within the system need to act with integrity and honesty. That’s exactly what our two Greens senators did."
"They took responsiliblty. They didn’t seek to blame anyone else for their actions."
Richard di Natale has also echoed calls from One Nation for a full audit of every federal politician's elligibility and citizenship status, to be carried out by the President of the Senate and the Speaker of the House.
