Former federal Labor leader Mark Latham is joining Pauline Hanson's One Nation as an upper house candidate for the NSW state parliament.
Mr Latham will also lead the NSW branch of the party, campaigning on immigration, congestion and over-development in Sydney.
"One Nation has the policies and NSW certainly needs a third choice - Labor and Liberal are on the nose," he told 2GB radio on Wednesday.
"I want to provide people with a choice, a third choice, to say you can vote One Nation and have practical, common sense solutions to these big issues in our state."
In response to the news, former Tasmanian Labor premier David Bartlett called him a "sick, sad, sorry loser".
The one-time Labor leader did ads for both One Nation and the Liberal Democrats during this year's Longman federal by-election, earning him the title of "king rat" from his former party colleagues.
Mr Latham led Labor to a solid defeat against John Howard in 2004 before quitting federal parliament in 2005.
He says he was sacked as a columnist for Australian Financial Review in 2015 for making offensive comments about domestic violence campaigner Rosie Batty.
Mr Latham was also turfed from a co-hosting role on Sky News for making offensive remarks.
Australian Associated Press