The ongoing citizenship crisis has taken another twist with a Liberal candidate blocked from replacing former minister Fiona Nash by the High Court.

Ms Nash was disqualified by the High Court on October 27 because she held dual citizenship, in breach of section 44 of the constitution.

Hollie Hughes was the next candidate down the NSW Coalition Senate ticket behind the then-Nationals deputy leader at the 2016 election, and was due to take Ms Nash’s seat following a court-ordered special count.

The court is yet to publish its reasons for the unanimous decision against Ms Hughes’ position.

It is expected if there is another special count the seat could go to Liberal candidate, Major General Jim Molan, a key ally of Tony Abbott.

Doubts were raised over Ms Hughes’ eligibility because she had taken up the position of part-time member of the Administrative Appeals Tribunal on July 1 this year.

Jim Molan was after Ms Hughes on the NSW Coalition senate ticket at the 2016 election.

Under the constitution, an AAT job is an “office of profit under the crown”, which would disqualify a person from Parliament.

The High Court on Wednesday considered whether Ms Hughes, who quit the AAT job on October 27, should be allowed to replace Ms Nash.

Solicitor-General Stephen Donaghue argued Ms Hughes should be duly elected because the process of “being chosen” for parliament started with nomination and concluded at the end of polling day.

He said taking up the AAT job 12 months after an election, and quitting it as soon as she knew she could be in line to fill the Senate seat, should not disqualify her.

However, Geoffrey Kennett SC – the barrister appointed by the court to argue the contrary case – said the fact that she held the AAT position between September 4-5, when the Senate resolved to refer the Nash case to the court, and October 27, should render her ineligible.

Mr Kennett said there was a “risk to responsible government” in allowing a failed candidate to take up a government position and then resign it to take up a seat in parliament.

He rejected the argument that the “choosing” process ended on election day, saying there were other methods of “choosing”, including Senate casual vacancies and in the case of an automatic win, when only one candidate stood in a seat.

The court also heard there was nothing preventing the Senate from referring Greens senator Andrew Bartlett for examination as to his eligibility.

Senator Bartlett was elected via a court order, which allowed him to replace Larissa Waters, who was disqualified because of her dual citizenship.

He has fended off suggestions his university job was an “office of profit under the crown”.

-AAP