The man in line to replace Larissa Waters as the Greens senator for Queensland has dismissed suggestions he might be ineligible to sit in federal parliament.
Andrew Bartlett, who was second on the ticket at the 2016 election, worked for the Australian National University at the time of nomination.
Under section 44 of the constitution, a person cannot sit in either house if they hold "an office of profit under the Crown".
But Mr Bartlett, a former senator and leader of the Australian Democrats, said it was incorrect to assert a university position is an office of profit.
"We've had strong advice to the contrary for some years and people have elected to parliament previously without resigning their university position," he said.
Advice provided to the Greens by the National Tertiary Education Union in 2013, and reissued last year, said that was backed by a "fairly overwhelming weight of opinion".
However, it noted it wasn't able to give "any absolute definitive advice" on the question of university staff because the specific issue has never been considered by the courts.
The memo noted that in the 1990s, Phil Cleary was disqualified after being elected to the lower house as an independent because he was employed by the Victorian government as a teacher.
On the other hand, Greens MP Michael Morgan election in 2002 was never challenged in the High Court even though he worked at the University of Wollongong.
Ms Waters resigned on Tuesday after discovering she remained a dual citizen, despite leaving Canada when she was 11 months old.
It came just days after Greens colleague Scott Ludlam stepped down when he found he still held citizenship in New Zealand.
The constitution does not allow people with dual or multiple citizenship to sit in federal parliament.
Senate President Stephen Parry has written to the governors of Queensland and Western Australian notifying them of the resignations of Ms Waters and Mr Ludlam.
He told the governors he could not advise them on how the seats should be filled until the High Court, sitting as the Court of Disputed Returns, made its determinations on their eligibility.
Senator Parry will report to the Senate when it returns on August 8 and it is expected the upper house will pass a resolution to refer the two cases to the High Court.
If the court finds the two senators were ineligible, the next candidate on the 2016 Greens tickets in Queensland and WA will fill the seats.
Malcolm Turnbull doesn't believe the clause that bans dual-citizens running for office needs changing.
"I don't think it is unreasonable for the constitution to require, if you want to be a member or a senator in the Australian parliament, you should be a citizen of only one country and that's Australia," the prime minister told Neil Mitchell on 3AW on Thursday.
Meanwhile, as he looks to replace his deputy leaders, Greens leader Richard Di Natale is seeking documentation that confirms he is not an Italian citizen.
