The Liberal-turned-Conservative senator Cory Bernardi will quit politics by the end of the year, after failing to make his start-up Conservatives party the dominant right-wing political force in Australian politics.

The South Australian, who has voted with the government on almost all legislation since his defection in February 2017, confirmed his decision to The Sydney Morning Herald and The Age on Tuesday night.

Senator Cory Bernardi is leaving federal politics. Credit:Alex Ellinghausen

"I realise that my enthusiasm to return to Parliament in the new year had gone and it's time to move on with other aspects of my life and let others pick up the cudgels," he said.

Senator Bernardi had hoped to steal One Nation votes in forming his breakaway party, but has failed at every election since to make any gains.