One Nation senator Rodney Culleton is one step closer to holding on to his new job.

Senator Culleton successfully applied to the Armidale Local Court, in regional NSW, on Monday to have a larceny conviction annulled.

The West Australian senator was convicted in his absence earlier this year for stealing a tow truck key from a driver who was trying to repossess one of his company cars in Guyra in 2014.

Magistrate Michael Holmes granted Senator Culleton's annulment application and set aside the March 2016 larceny conviction in absence.

Senator Culleton has pleaded not guilty to the larceny charge and the case was adjourned for mention until September 12.

Larceny carries a maximum penalty of five years' jail, which could deem him ineligible to be a senator.

The constitution says anyone convicted of a crime that has a punishment of at least one year's jail can't be a member of parliament.

If he is found to have been disqualified at the time of election, a recount will be held to determine who replaces him as a WA senator.

It's a different circumstance to a senator who becomes disqualified after being elected, in which case the One Nation party would choose his replacement.

Senator Culleton, who failed to attend a court hearing earlier this year, was arrested on Monday morning after handing himself in to Armidale police.

NSW police had been granted an arrest warrant in July 2015, having faced difficulties trying to serve a court attendance notice on Senator Culleton.

He branded it "political persecution" in a Facebook post on Monday.

Senator Culleton is also awaiting trial in WA later in August - the week before parliament begins - after he was arrested and charged for allegedly stealing a car being used by receivers from RSM Bird Cameron as they began foreclosure proceedings at a friend's farm.

The senator won the 11th spot on the WA ballot.