One Nation senator Rod Culleton is expected to face a High Court challenge to his eligibility to run for parliament.
The federal government has revealed plans to ask the Senate to refer his case to the High Court over an annulled larceny conviction that stood at the time of the election on July the 2nd.
Under the constitution, a conviction on an offence which carries a jail term of a year or more disqualifies a person from sitting in parliament.
West Australian Senator Culleton has told Sky News he's not sure whether he would cooperate.
"There seems to be a very dark cloud hanging over the High Court at the moment. And one needs to see where that is going to go. And until that answer comes back, I don't know if I am going to participate in any High Court jurisdiction."
The news regarding Senator Culleton comes just days after Family First Senator Bob Day formally resigned from parliament, after his building company went into liquidation.
The federal government says the expected referral of the two crossbench senators to the High Court will not deter its legislative agenda in the upper house of parliament.
Both were expected to support the government in the passage of key legislation.
Attorney-General George Brandis has told the ABC their absence won't upset the government's plans in the Senate.
"In relation to Senator Day, there's simply a vacancy. There's been a resignation, but because of the peculiarity identified, the possible Section 44-5 issue, then that vacancy can't be filled until the High Court, sitting as the Court of Disputed Returns, deliberates on the matter and the validity of Senator Day's election in the first place. Of course the government is committed to its agenda. We have a legislative agenda. We have a very full legislative agenda in the final three weeks of this parliamentary year. So the government will be undeterred in prosecuting its agenda."
Under the constitution, a conviction on an offence which carries a jail term of a year or more disqualifies a person from sitting in parliament.
The 2014 New South Wales conviction was later annulled, but Senator Culleton pleaded guilty to the charge at a subsequent hearing with no conviction recorded.
Mark Dreyfus is Labor's legal affairs and national security spokesman.
Speaking to the ABC he's asked why it has taken so long for the Turnbull government to make the information about the two Senators public.
"We don't know the details of the basis of the reference, but it is more chaos in the Senate. What we do know is that the Attorney-General has been sitting on this as has the government been sitting on the details in relation to Bob Day. And Senator Brandis needs to explain himself. Why is it that this had to wait too until the day after there was a reference announced for Bob Day?"
The Turnbull government has heavily relied on One Nation and Family First to get its legislation through the upper house, which returns on Monday.
Senator Culleton has indicated he'd abstain from voting while any court action goes on.
