A judgment ordering One Nation senator Rod Culleton and his wife to pay a former Wesfarmers director more than $200,000 in damages was upheld on Thursday, as a new challenge to his eligibility to sit in Parliament was launched by a former business partner.

The judgement relates to a December 2009 deal the Culletons inked with Dick Lester's Balwyn Nominees for land near Williams in Western Australia's Wheatbelt region so the couple could expand their oat farming operation.

Rod Culleton, Senate candidate for WA.

The Culletons agreed to buy most of the property, named Rathgar, for $13.2 million and lease the remainder for one year for $500,000 excluding GST.

But when the first rent instalment was due less than three months later, Senator Culleton told Mr Lester he had cashflow problems and the deal was terminated within a fortnight.