Andrew Hastie says he supports Sussan Ley and anyone suggesting otherwise is “being mischievous” after his latest policy intervention further fuelled speculation of a leadership tilt.

The shadow home affairs minister’s personal crusades on abandoning net zero by 2050, “Australia-first” manufacturing and cutting net overseas migration have caused ructions inside the party and prompted speculation he is laying the groundwork to fulfil a long-held ambition of leading the party.

The West Australian MP sought to hose down the prospects of a challenge on Thursday, telling 2GB that he supported Ley and “anyone who is speculating otherwise is being mischievous”.

“I’m a team player, I’m just being a little bolder in some of the policy positions that I think we should adopt. There’s work to be done, but these are pretty straightforward, principled positions which I think a lot of people are looking for us to adopt,” Hastie said.

Senior Liberal sources told Guardian Australia that Ley’s leadership was safe for now, with only a small rump of hardline rightwingers agitating behind the scenes.

In the latest in a series of provocative policy statements, Hastie warned on Wednesday that the Liberal party could “die” as a political movement if it did not commit to cut overseas migration levels, which he blamed for making Australians “feel like strangers in our own home”.

The social media post noted net overseas migration was 446,000 in 2023-24 but did not mention it had fallen from a peak of almost 556,000 in the year to September 2023.

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Treasury assumes net migration will fall to 262,000 this financial year and then to 225,000 in 2026-27.

The home affairs minister, Tony Burke, said Hastie needed to “decide whether he’s happy with modern Australia or not” as he challenged him to detail what specific visa programs a Coalition government would cut to further reduce migration levels.

“If he wants to make cuts further, he needs to say where. Does he want to make additional cuts to skilled migration? If that’s what he wants to do, can he nominate which aged care centres he believes should close? Because without immigration, we don’t keep them open,” he said.

Immigration was a major Coalition priority under former leader Peter Dutton, who promised dramatic cuts to permanent migration and net overseas migration after attempting to link the post-pandemic influx of people to housing supply and affordability.

While the migration policy under Ley has yet to be settled, the new shadow immigration minister, Paul Scarr, has promised a more empathetic tone when talking about migrants.

Scarr declined to defend Hastie’s views on immigration but supported his right to weigh in as shadow home affairs minister during an at-time tense interview on ABC Melbourne.

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Asked if he was comfortable with Hastie’s “strangers in our home” comment, the Queensland senator sidestepped the question.

“My preference is to come back to the factual matters, the realities around issues in relation to our housing supply, the need for long-term planning and the need for the government to be transparent with the Australian people,” Scarr said.

In his interview on 2GB, Hastie doubled down on claims the Liberal party could perish if it did not pledge to curb migration levels.

“Unless we get our act together, we’re going to be potentially in further decline and perhaps one day extinct,” he said.

Hastie said a motivation for his policy campaigning was his concern about the “fragmentation” on the conservative side of politics as the Liberals battled with One Nation and minor and micro-parties for votes.

“I’m simply stating some positions, mainly through social media, and people can interpret that how they want, but I just think we need to reconstitute our natural constituency on the centre-right if we’re going to be a force to beat Labor in two years,” he said.