Angus Taylor has shut down Andrew Hastie's push for the Liberals to be "open-minded" to increasing taxes on gas companies and winding back concessions for property investors, exposing a clash of philosophies between the opposition leader and his most likely future rival.
The opposition leader also did not repeat Hastie's criticism of Donald Trump as he refused to say whether or not he endorsed the US and Israel's war with Iran.
The shadow industry minister has been mounting the case for the Liberals to shed their conventional neo-Liberal economic mindset - including support for big businesses - to help win over disillusioned voters switching to One Nation.
Echoing comments to Guardian Australia's Australian Politics podcast, Hastie on Sunday confirmed he was open-minded about increasing taxes on gas exports and winding-back the capital gains tax discount and negative gearing concessions.
"I just think we need to overhaul the whole system. We either fix the system, or it's torn down by people like Pauline Hanson," Hastie said in a interview with ABC's Insiders program, in which he also declared that "no one's going to reward us for a final last stand for neo-Liberal politics".
On Monday, Taylor dismissed the prospect of supporting the contentious tax changes, repeating his view that "If you whack a tax on something, you get less of it".
"It's pretty straightforward for me. And I think that is a longstanding understanding of the economics profession in the Liberal party. So if we want more of something, let's not tax it more,"
he told reporters in Canberra.
The split on tax is emblematic of a deeper philosophical clash between Hastie and Taylor, which some colleagues believe will evolve into a broader conversation about who is best placed to lead the party, particularly against the rising threat of One Nation.
Hastie wanted to challenge Sussan Ley earlier this year but was convinced to pull out for Taylor, who returned the former solider to the frontbench after the successful leadership spill.
The two men are from the same right faction but have different worldviews: the Oxford-educated Taylor is considered a classic free-market Liberal while Hastie favours a more interventionist approach to "re-industrialise" Australia.
The Albanese government is modelling a new windfall profits tax on gas companies and changes to the capital gains tax discount and negative gearing ahead of the May budget, meaning the opposition could be forced to agree a position within coming months.
Guardian Australia has spoken with several Liberal MPs, who believe the Coalition must at least consider softening their hostility to new taxes.
Anne Ruston, a Liberal frontbencher said "we should have everything on the table".
"I support us having a conversation about anything that is going to improve the lot of Australians - that doesn't mean in this conflict, it means more generally,"
the shadow health minister told ABC's RN Breakfast.
"We haven't had an honest conversation in this country about issues around taxation for a very long time because the conversation always gets shut down."
Hastie has become increasingly strident in his criticism of Trump and the war in Iran, splitting from his colleagues who have offered full-throated support for the conflict.
Taylor did not respond directly when asked on Monday if he supported Trump's war, instead emphasising the need to re-open the strait of Hormuz to ease the global fuel crisis.