One Nation senator Rod Culleton says he's unfazed by a bid to oust him from parliament, vowing to fight whatever critics throw at him.
A former associate, Bruce Bell, has petitioned the High Court to disqualify Senator Culleton, arguing he was ineligible to nominate because of a larceny conviction in NSW.
The 52-year-old former farmer also faces a stealing charge in WA relating to a $27,000 hire car, which he allegedly surrounded with hay bales to thwart bank-appointed receivers during foreclosure proceedings.
The larceny conviction - over a $7.50 key he took from a tow truck driver who was trying to repossess a lease car - has since been annulled as it was recorded in his absence after he failed to attend court.
The matter is due to return to an Armidale court next month.
"It would be a question of perhaps our side and the prosecuting sergeant sitting down and using common sense, and working it out," Senator Culleton told AAP on Monday.
"The burden of proof is on them now so good luck to them.
"I'm not overly concerned about it.
"It's up to them now how they want to go about it."
Senator Culleton said court costs for the matter were mounting but he believes he'll win and would seek to get them back.
He also believes the prosecutions are politically motivated.
"Someone's driving it - I don't know who is driving it.
"I'm prepared for whatever comes at me. I'm not backing down because criminal is personal."
Senator Culleton also believes Mr Bell is using him as "a political prop".
"These are all guys who think they can jump on my coat-tails," he said.
In his petition filed last week, Mr Bell asked the High Court, sitting as the Court of Disputed Returns, to order fresh elections for the 12 Western Australia Senate seats.
The documents, tabled in federal parliament on Monday, say Senator Culleton's seat should be declared vacant, with the 13th-ranked election candidate - The Nationals' Kado Muir - replacing him until a new election can be held.
Mr Bell also alleges Senator Culleton was ineligible to nominate because he was bankrupt, which the parliamentary newcomer flatly denies.
The Australian constitution bans people from being federal MPs if they are awaiting or serving sentences for crimes that carry sentences of 12 months' jail or more - which applies to both of Mr Culleton's charges.
