Federal Liberal MP Russell Broadbent has quit the party to sit on the crossbench after he was dumped from preselection.
The MP for the Victorian seat of Monash, who was first elected in 1990, told coalition colleagues in Canberra on Tuesday he would see out the rest of his term as an independent.
Mr Broadbent will be replaced as Liberal candidate for Monash by community leader Mary Aldred, following a preselection ballot on Sunday.
Ms Aldred reportedly won the preselection by 161 votes to 16.
In a statement, Mr Broadbent said he would remain a Liberal at heart but the preselection outcome had sent an obvious message.
"On Sunday, there was a preselection where I received less than 10 per cent of the vote. This was a clear signal from members and one which I believe revokes my licence to represent the Liberal Party in the electorate of Monash," he said.
"As I said in the party room this morning, I believe there are storm clouds ahead for this nation, and I strongly encouraged the party to support the leader."
It had been an honour to stand in the parliament as a Liberal member, he said.
Mr Dutton said it was "regrettable" the Monash MP had made the decision, but thanked him for service to the party over many decades.
Mr Broadbent, who has been a member of the Liberal Party since 1980, is understood to be taking medical leave before returning to parliament.
Since the 2022 election, there have been two by-elections for coalition seats held by former ministers Alan Tudge and Stuart Robert.
The Liberals lost Mr Tudge's seat of Aston to Labor but retained Mr Robert's seat of Fadden.
Nationals MP Andrew Gee moved to the crossbench in support of the Indigenous voice in December.
Prime Minister Anthony Albanese told a Labor caucus meeting it appeared Mr Dutton's key priority was to keep his party together.
Victorian Liberal leader John Pesutto, whose first political job was working for Mr Broadbent in the 1990s, said he was "disappointed" in the decision to walk away from the federal parliamentary Liberal party.
But he said he "couldn't be happier" that Ms Aldred had been preselected.
"She's going to be a star," Mr Pesutto told reporters at Victorian parliament.
