David Ettridge, a co-founder of One Nation, has accused the party of abandoning him with huge debts from when he was jailed alongside Pauline Hanson.
In 2003, Mr Ettridge and Ms Hanson were imprisoned for electoral fraud but released months later after their convictions were quashed by a Queensland Court.
Mr Ettridge said his legal ordeal cost him his house and his personal wealth.
He told the ABC's Four Corners program he had sought compensation from One Nation — joining a number of former officials and candidates speaking out about the party's administration.
Mr Ettridge described One Nation as a party "in a degree of turmoil".
"[Pauline Hanson] weaknesses are, I think, that she is out of her depth, doesn't really understand what she's doing and how to do it," he said.
He and Ms Hanson fell out after their convictions for electoral fraud were overturned, and they were released from prison.
Mr Ettridge said he spent his own money defending himself on the basis that the party would pay him back.
He claims the money never materialised and now he wants compensation.
"I put a claim in to the party for a $150,000, which is only a fraction of the damages that I believe I'd incurred and it was denied," he said.
"And I believe they were honour bound and legally bound to settle with me — they took the view that they were not going to."
Documents show One Nation rejected Mr Ettridge's claims and asked him to stop contacting the party.
He also wrote to senator Brian Burston asking to be included in any Senate inquiry into Ms Hanson's conviction and jailing.
Senator Burston replied with what Mr Ettridge described as a "go away" email.
Hanson 'putting her interests above voters'
Mr Ettridge is one of many former One Nation officials and candidates who have made public their concerns about the direction of the party under Ms Hanson and her chief advisor, James Ashby.
He said One Nation supporters deserved a voice, but Ms Hanson was putting her own interests above those supporters.
"When it (One Nation) was started it met the needs of a lot of people with a lot of concerns about globalisation," he said.
"Today people are concerned with the changing cultural mix of Australia and what's happening in Europe and other countries, it's a serious concern for a lot of people.
"But I think the problem we have is that the One Nation party went to the federal election with a lot of promises, and they haven't delivered on them.
"It's become a Pauline Hanson dictatorship, if you don't agree with Pauline — she wants to fill the party up with people who say yes.
"And if you disagree with her, or you work closely with her and lose respect for her, or give advice it's not respected or accepted — Pauline is in full control."
When Four Corners contacted Ms Hanson and Mr Ashby about Mr Ettridge's claims, they declined to be interviewed.
Watch the Four Corners episode on ABC iView.