One of the government's rising conservative figures has taken aim at Cory Bernardi for not fronting a meeting of Liberal MPs to explain his reasons for defecting from the party.
Andrew Hastie, who describes Senator Bernardi as a good friend and someone he respects, is disappointed with the renegade's behaviour.
"I wish that he had attended the Liberal Party room meeting this morning, looked us all in the eye and explained his reasons," the Liberal MP posted on Facebook on Tuesday.
"He was elected as a Liberal Party senator and owes his colleagues an explanation. Party members and voters will be rightly disappointed."
Mr Hastie, elected to the West Australian seat of Canning in 2015 after the sudden death of incumbent Don Randall, warned the political system couldn't afford further fragmentation.
Senator Bernardi's move would only worsen the legislative gridlock in the upper house.
"Our political institutions are fragile and all MPs need to work together - as far as our convictions will allow - to deliver reform that keeps Australia safe and prosperous," Mr Hastie wrote.
The MP said his own heart was firmly with the Liberal Party.
Fellow backbencher Russell Broadbent is said to have also criticised Senator Bernardi for not turning up to the meeting.
Former prime minister Tony Abbott says he is disappointed more effort has not been made to keep the Liberal Party united.
"The Liberal Party needs more people, like Cory, who believe that freer citizens will make a fairer society and a stronger country and who are prepared to speak out and make a difference," he posted to Facebook on Tuesday.
"No government entirely satisfies all of its supporters. This is not an argument to leave; it's a reason to stay in and fight more effectively for the things we believe in."
He urged supporters of "smaller, stronger" government to stick with the Liberals.
"That is the only way to improve our party, our government and our country," Mr Abbott said.
The Australian Christian Lobby lamented the further fragmentation of politics but hoped it would offer "greater competition for voters who care about marriage, freedom of speech and the truth about gender".
"Disruptions like Trump and now Bernardi here may sadly be what is needed to cause politics to become more responsive to mainstream concerns again," director Lyle Shelton said in a statement.
