A legal twist has occurred in Jim Molan's bid to take the NSW coalition Senate seat initially vacated by former minister Fiona Nash.
Liberal candidate Jim Molan's bid to take up a Senate seat has hit a hurdle as the High Court seeks to work out whether he has a three or six year term ahead of him.
The Senate agreed after the 2016 double-dissolution election that six-year terms would go to the first six senators elected in each state and three-year terms to the bottom three.
In NSW, this meant coalition senators Marisa Payne, Arthur Sinodinos and Fiona Nash were given six-year terms, and Concetta Fierravanti-Wells and John Williams had three-year terms.
Ms Nash was found to be disqualified by the court in October over her dual citizenship.
She was to be replaced by the next coalition candidate on the 2016 election ticket, Hollie Hughes, but Ms Hughes was found by the court to be disqualified because of her job with the Administrative Appeals Tribunal.
Mr Molan was the next candidate after Ms Hughes on the coalition's ticket and was due to be declared elected on Monday following a special count by the Australian Electoral Commission.
The summons filed by the government declaring Mr Molan's election suggested he was filling the place for which Ms Nash was elected.
Barrister Geoffrey Kennett SC, who was appointed by the attorney-general to be a contradictor in the case, said in fact Senator Fierravanti-Wells was elected for the place for which Ms Nash was returned - giving her the six-year term.
In turn, Senator Williams was elected for the place for which Senator Fierravanti-Wells was returned and Mr Molan filled Senator Williams' spot.
Mr Molan agrees.
"My expectation is I will come in at the bottom somewhere and I will get the remainder of the three-year term," he told Sky News.
Senator Fierravanti-Wells has been allowed to be a party to the case which will go to a directions hearing in front of Justice Stephen Gageler on December 22.
The issue could then either be dismissed or referred to the full court for consideration in January.
Senator Williams signalled this year he intended to retire at the next election.
The court was also told there were no eligibility issues with Mr Molan taking the seat, in terms of his citizenship or any other issues under section 44 of the constitution.
Mr Molan's counsel Arthur Moses QC said there was some urgency in resolving the matter as the Senate returned on February 5 and NSW had been without one of its senators "for some time".
The case could have implications for two other cases involving former Tasmanian senators Jacqui Lambie and Stephen Parry, who quit over their dual citizenship.
Ms Lambie and Mr Parry had six-year terms.