Former One Nation senator Brian Burston is joining mining magnate Clive Palmer's new political party.
Senator Burston announced his move to the billionaire businessman's United Australia Party just minutes after telling the upper house he would sit as an independent.
"We will unite Australia and we will bring integrity back into the Senate and provide policies and vote on policies that the government might bring forward, that will benefit all of Australians," the NSW senator told reporters in Canberra on Monday.
Asked whether he had lied to parliament, Senator Burston claimed he'd only made the decision to join the rebadged party after addressing his chamber colleagues.
Mr Palmer praised his new recruit's political courage.
"I am very happy to say that Brian has shown a great amount of courage and a great amount of foresight to stand up for the people who elected him, to aim for their aspirations," he told reporters.
"I look forward to a long and happy relationship with him."
During a fiery press conference, Mr Palmer fended off a barrage of questions about money owed to axed workers at his mothballed Queensland Nickel refinery.
Earlier, Labor senator Murray Watt said Senator Burston would be joining "another circus" if he linked up with Mr Palmer.
"His name is mud in Townsville and in much of Queensland because of the way that he has run his businesses into the ground and ripped off working people," he told reporters.
"If Brian Burston decides to sign up with Clive Palmer then I think his political career is even more short-lived than it currently stands."
Treasurer Scott Morrison didn't mince his words on Mr Palmer's political resurrection under a new party name.
"Look, I think people out in Australia would say, the circus doesn't need another sideshow," Mr Morrison told ABC radio.
Former Liberal prime minister Tony Abbott said voters were sick of people like Mr Palmer.
"We now know what he's like; he's driven every business that he's ever run into the ground, the money he's made has all been made by wheeling and dealing, not by building businesses up from scratch," he told Sydney radio 2GB.
"The last thing we need are more spivs in the parliament."
One Nation leader Senator Pauline Hanson now has only one parliamentary party colleague - Western Australia Senator Peter Georgiou.
Australian Associated Press
