Ahead of a crucial meeting of Liberal MPs and senators on Wednesday, party insiders say they will likely water down Australia's climate ambition if they return to government, while retaining a commitment to reaching net zero carbon emissions at some point.
Moderates, like NSW Senators Andrew Bragg and Maria Kovacic, have acknowledged they would quit the frontbench if net zero was ditched, while conservatives, like shadow defence spokesman Angus Taylor, are pushing for an end to the policy.
Mr Taylor said he wouldn't pre-empt the outcome of the meeting but the Liberal would not support "economically destructive and unachievable targets".
"So we won't be supporting Labor's failed net zero plan," he told Nine's Today Show on Tuesday.
"That I can guarantee."
Australia signed up to the Paris accord in 2015 under then-prime minister Tony Abbott, promising to limit its greenhouse gas emissions as part of a global push to tackle global warming.
Six years later, the Morrison government set a target of net zero emissions by 2050, and Labor has since set more ambitious climate goals including a 62-to-70 per cent reduction in carbon pollution by 2035.
Debate over the coalition's climate policy restarted in earnest after Labor's May election win, and the issue now threatens to engulf Sussan Ley's leadership.
Mr Taylor was last week spotted dining in Canberra with a splinter group of conservatives who have been vocal in their criticism of net zero, including putative leadership challenger Andrew Hastie.Â
It sparked rumours that Mr Taylor or Mr Hastie might be manoeuvring to challenge Ms Ley pending the outcome of this week's climate policy discussions.
But Mr Taylor brushed off suggestions he was planning a coup, but was less than effusive in his support of his leader.
"Well, that's just not right," he said.
"I'm focused on making sure we've got the policies we need coming together to hold this government to account and to be contestable at the next election."
When offered the opportunity to categorically rule out a challenge, he responded: "It's not something we're planning."
Labor frontbencher Amanda Rishworth, being interviewed on the program alongside Mr Taylor, was asked if she found his response convincing.
"Well, no," she demurred.
The Liberals' net zero debate comes after junior coalition partner the Nationals announced a plan to ditch a formal climate target and instead tie emissions reductions to an average of OECD countries.
University of Queensland climate and environmental law expert Justine Bell-James said any move to weaken Australia's targets would be in breach of the Paris accord.
"Under the Paris agreement countries have to make these pledges every five years," Professor Bell-James told AAP.
"Because of this mechanism that they call the ratchet mechanism, each successive one needs to be an increase in ambition."
Latrobe University climate law expert Julia Dehm agreed, saying a future government would "certainly" be in breach of the Paris agreement if it went back on its promises.
Dr Dehm said a ruling from the International Court of Justice in July that all countries had a legal obligation to tackle the "urgent and existential threat" of climate change was an additional barrier to watering down Australia's climate targets.
"There is the potential for states to take Australia to the ICJ alleging that it hasn't fulfilled its international climate obligations," she said, adding that a weaker emissions reduction goal would also cause reputational damage for the government.
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