Senator Cory Bernardi confided in former prime minister Tony Abbott. Credit:Alex Ellinghausen The two canvassed a range of options, including the much-speculated defection. Bernardi was dismayed when several days later details he had only confided to Abbott turned up in The Australian newspaper. In subsequent articles Abbott himself would be quoted urging against any split. Mr Abbott told Fairfax Media on Monday he has "never" leaked to The Australian. Feeling betrayed by a man whom he had loyally supported, Bernardi added it to the list of other ailments he felt had infected Australian politics. Bernardi first sensed a problem in 2009, when during a heated and divisive partyroom debate on whether the Coalition should support Kevin Rudd's emissions trading scheme, one of his colleagues, the now deceased West Australian MP Don Randall, rose to his feet and said: "I don't give a stuff about the national interest, I want to get re-elected and this needs to go away." Bernardi went back to his Senate office and wrote down the quote. He never forgot it. It was the beginning of the end.

Senator Cory Bernardi at a joint partyroom meeting in Canberra last year. Credit:Alex Ellinghausen Bernardi and colleagues, including his mentor Nick Minchin, won that fight. The Coalition toppled Malcolm Turnbull and installed Abbott as leader. Abbott had previously taken the Randall approach and advocated approving the ETS to get it off the table but this was all forgotten after he adopted his new position with zeal and campaigned against a "great big new tax". His success spooked Labor into making what was once an unprecedented move in rolling a first-time prime minister. "I have not the slightest recollection of the claimed conversation with colleagues and I don't leak, even to The Australian," Tony Abbott told Fairfax Media. Credit:Peter Braig But the weathervane approach to politics Abbott had showed on climate change policy continued in government, weakening support among traditional Liberal Party voters, who at the last election looked to other parties, including the populist One Nation.

In opposition he made one of his infamous "captain's calls" and switched Coalition policy to support recognising local government in the Constitution. Senator Bernardi led calls for the position to be reversed and, at the very least, debated. Illustration: Ron Tandberg Once more he was having the same policy fight under the same leader. Was it 2009 or 2016? He couldn't tell He continued campaigning on issues such as banning the burqa, opposing same-sex marriage and lower taxes, only to be mocked by Abbott and urged to pipe down by his formidable chief of staff Peta Credlin. In the first weeks of his prime ministership Abbott said of Bernardi - in front of a group of backbench Coalition MPs - that the conservative senator should already be in cabinet and would be "as soon as he stops talking about the things he is always talking about".

"I have not the slightest recollection of the claimed conversation with colleagues and I don't leak, even to The Australian," Abbott told Fairfax Media on Monday. Abbott went on to make a series of political and policy decisions Bernardi despaired over. He even crossed the floor. The internal fights grew tiring. He felt his only job was trying to save the party from itself. But the final straw came late last year when he returned from secondment to the United Nations in New York. Fresh from watching Donald Trump's colossal disruption of the political establishment in the US, Bernardi found himself once more campaigning against his own government, this time railing against what looked like early moves to introduce a form of a market-based carbon price. Once more he was having the same policy fight under the same leader. Was it 2009 or 2016? He couldn't tell. It confirmed for him that the party was spiralling and it didn't matter who was the leader. On Tuesday he will walk into the Senate chamber as he has done thousands of times. But now, he will take a seat in unfamiliar territory on the crossbench.

The voters who abandoned the party in 2016 for One Nation, the Australian Liberty Alliance and others, will be offered a new choice and voice on the right. At worst, Bernardi will end up a lone protest vote in the Senate. But cabinet ministers worried about the recent speculation of a split fear this won't happen. Instead they despair that a Bernardi breakaway could have more impact than a leadership change by triggering a structural upheaval of the Liberal Party and Coalition. Loading Has Australia's disrupter arrived? Follow us on Facebook