Democratic Labour Party senator John Madigan has quit his party but will remain in parliament as an independent.
The Victorian senator said the party had become infected by the "cancer of political intrigue" and had been a distraction during his time in the upper house.
"It has become apparent to me that the DLP's own worst enemies are within its own ranks," he told parliament on Thursday.
"I've witnessed first-hand attempts by those in the party to assume power at any means even if it means the very destruction of the party itself."
Senator Madigan said he had become the victim of a DLP attack after hiring a party-recommended office manager.
"That person systematically ran a campaign of disinformation and disharmony in my office," he said, adding confidential information was leaked and lies were told.
Senator Madigan, who has been a member of the DLP for eight years and the first party member in federal parliament for almost 40 years, will remain on the crossbench as an independent.
He says he remains committed to DLP values.
Senator Madigan sought to table documents relating to his resignation but was prevented from doing so until all senators had seen them.
The documents may be tabled, and therefore made public, later on Thursday.