Jacinta Nampijinpa Price has publicly endorsed Andrew Hastie as a future Liberal leader in a fresh threat to Sussan Ley’s attempts to unite the fractured party.

Price has swung in behind the West Australian MP as the former solider’s personal campaigns on net zero and manufacturing policy stoke fresh division inside the party and renew internal speculation about a future leadership challenge.

After last week threatening to quit the shadow frontbench if the party re-committed to net zero by 2050, Hastie this week turned on the “nameless cowards” within the party who provided anonymous quotes to The Australian urging him to tone down his freelancing.

The internal row came after Hastie posted a social media video advocating a revival of domestic manufacturing, in which he blamed both major parties for killing Australia’s car-making industry.

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“We’re a nation of flat-white makers, when we could be making beautiful cars like this again,” Hastie said, standing alongside a 1969 red Ford Falcon.

Hastie’s “Australia-first” pitch was widely viewed internally as an alternative policy vision from an aspiring future leader, particularly given manufacturing falls outside his home affairs portfolio.

The former Special Air Services captain did not contest the Liberal leadership after the May election but has repeatedly spoke of his desire to one day fill the role.

Price leapt to her colleague’s defence on Wednesday, suggesting his internal critics were agitating because they saw him as a threat.

“I think they probably see him as some kind of threat, because he is so good at what he does,” she told 2GB.

Asked if Hastie was capable of leading the Liberal party, Price said: “I think so.”

“The topics that I spoke to at Cpac [conference], which I think we should be focused on our key institutions, which are family, community and our nation – I think are at the core of [what] Andrew Hastie’s leading with,” she said.

“I think he’d make a remarkable leader one day.”

The Liberal MPs Garth Hamilton and Henry Pike have also publicly endorsed Hastie as a future leader in recent days. Guardian Australia has spoken to two other Liberal MPs who share the same view.

Price was this month dumped from the shadow frontbench after refusing to support Ley’s leadership or apologise for suggesting, without evidence, the federal government was bringing in Indian migrants to win votes.

The Northern Territory senator refused to endorse Ley again on Wednesday.

She vowed to continue to fight alongside Hastie for the Liberal Party to dump net zero.

“We don’t have much in way of policy,” she said the Liberals’ agenda, which put all of its policies – including net zero – up for review after the election defeat.

“We are supposed to be an effective opposition. We do want to be able to do our job, so we’re not going to sit back and be silent until such time as we have policy positions on a number of issues.”