While his defection has emboldened some conservatives who believe Mr Turnbull should pay more heed to the right-wing of the party, confirmation of his defection has united his soon-to-be former colleagues against him.

Immigration Minister Peter Dutton, one of the most senior conservatives in the government, lashed out, saying Senator Bernardi's actions would only split the conservative vote and facilitate the election of a Labor government.

"I think people will be angry about any defection, angry about the betrayal of the Liberal Party values," he said.

He scoffed at suggestions other MPs would follow the renegade who has been unhappy in the party for several years, under Tony Abbott and Mr Turnbull.

Financial Services Minister Kelly O'Dwyer said Senator Bernardi was on an ego trip and should have been "upfront and honest" with voters before the last election.

"They want to know that parliamentarians who are sent to Canberra are focused on their interests and focused on the broader national interest," she said.

"I think that people would feel that their trust has been violated if somebody stood for a particular political party and then left that political party, particularly so soon after an election campaign."

Defence Industry Minister Christopher Pyne said Senator Bernardi should quit Parliament and recontest his seat, while Treasurer Scott Morrison accused him of betraying the Liberal Party and its voters.


Trade Minister Steven Ciobo said Senator Bernardi had spent his whole career causing internal trouble and "had never laid a glove on the Labor Party".

"He was elected off the back of the Liberal Party, it wasn't because he was Cory Bernardi," Mr Ciobo said, echoing calls he should quit the Senate.

At the election, Senator Bernardi received 2043 first preference votes, or 0.025 per cent of a quota. The SA Liberal Party received 345,767 votes.

Education Minister and South Australian Liberal Senator Simon Birmingham said Senator Bernardi has betrayed Liberal voters and the party and should surrender the seat.

"There is effectively a contract that all of us undertake when we offer ourselves at election. We go to that election on the ballot paper, with not just our names, but also our party affiliation attached to that and that is an enormous guide," he said.

"I don't kid myself into thinking that there are hundreds of thousands of South Australians who know and like Simon Birmingham and choose to vote just for me."

SA Liberal MP Rohan Ramsey and Queensland LNP MP Michelle Landry said Senator Bernardi should quit the Senate and give his seat to a Liberal because it was the party's Senate spot, not his.


Another SA Liberal Sean Edwards, who lost his Senate seat at the last election, was scathing.

"It would be a gross departure as to - certainly six months into a six-year term - what people would have expected," he said.

"I would prefer to see Senator Bernardi stay within the Liberal Party and do the work that all the members that preselected him in preference to members like myself (expect)," he said.

Liberal Democrat Senator David Leyonhjelm said Senator Bernardi would regret his move because he would lose his seat.

Labor leader Bill Shorten cashed in on the crisis.

"A government which can't govern itself can't govern the nation. It is long overdue for the government to focus on the jobs of other Australians," he said.

"I promise Australians that we will focus on jobs, saving Medicare and of course making sure that housing is affordable for all Australians."