The opposition leader has been accused of failing to articulate a way forward for the Liberals, who are edging closer to a final position on their energy and climate change policy.
After a fortnight of damaging infighting and wild leadership speculation, Ms Ley has called a series of party room meetings to bed down a new approach to energy and emissions reduction.
As the party prepares to negotiate its final policy, former Liberal leader John Hewson has delivered a withering assessment of Ms Ley and the party she leads.
"She hasn't shown any clear strategy, or any strong capacity in terms of leadership," he told AAP.
Mr Hewson, who let his membership lapse in 2019 because of concerns about the party's record on climate change, said the opposition was devoid of serious policies because its members had little experience outside politics.
"They haven't got people with significant business experience ... I don't think that they've got people who are policy wonks in economic policy," he said.
"You can't just keep being negative and hoping to win on criticism, as (Tony) Abbott did."
As opposition leader, Mr Hewson took a highly detailed promise of economic reform to the 1993 federal election, which the coalition roundly lost to Paul Keating's Labor government.
"I'd really like to see Sussan be given a fair run with everyone pitching in and doing a proper policy job," he said.
Mr Hewson was also highly critical of West Australian MP Andrew Hastie, who is widely considered a potential leadership contender.
"He's been sold a bit of a dump by the right of the party," the former Liberal leader said, arguing Mr Hastie's criticism of Australia's immigration program was unlikely to be popular in the broader electorate.
Mr Hastie is a vocal critic of Australia's climate targets, an issue the Liberals appear to be a step closer to resolving their differences over.
After weeks of internal brawling, a party room meetings have been called for next week to finalise the coalition's energy and emissions reduction policies.
Liberal members will discuss their energy and emissions-reduction policy at a party room meeting on Wednesday.
Shadow ministers will meet to formalise their position the following day.
But even if the Liberals land a cohesive plan amid fierce internal divisions, they will still need to strike an agreement with the Nationals.
A six-person committee - three Liberals and three Nationals - will attempt to reach a compromise on the issue ahead of an online hook-up of both party rooms on November 16.
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