Former frontbencher Arthur Sinodinos says his support for the Prime Minister is “not unconditional” in statements that will put more pressure on Tony Abbott.

The Prime Minister’s hold on the leadership is under threat, as Coalition MPs publicly call for him to be replaced, possibly by former leader Malcolm Turnbull or Foreign Minister Julie Bishop.

Senator Sinodinos, who stood aside as assistant treasurer last March after being named in a corruption investigation, is a highly regarded figure in the Liberal Party and a former chief of staff to John Howard.

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He said Mr Abbott needed to prove he could tackle some of the issues facing the Government.

“I’ve always supported Tony Abbott. My support for him has been based on his performance, his courage, his capacity to make the right calls for the country in opposition and in government,” he told Sky News.

“But that support ongoing is not unconditional.

“It’s based on being able to grapple with the issues we face at the moment, which appear to have impacted on our standing in the polls.”

But he said the “chatter” within the party about a change of leadership was “academic” until someone else declared their intention to run.

“It’s hypothetical to talk about a leadership contest,” he said.

“No-one’s put their hand up and no-one has offered an alternative program.

“Unless and until someone else declares, it’s academic to discuss the merits of other people because we don’t know what is on offer and what we are being offered.”

Senator Sinodinos said any debate about the leadership needed to include a review of policies, including the contentious GP co-payment, and he raised the possibility of dumping them.

“If some of our policies are not going down well with the electorate, do we try and sell them harder?

“Or do we just make a judgment that perhaps we’ve poorly designed them – do we just need to jettison them because we will not get public support for them?”

He said neither Ms Bishop nor Mr Turnbull should be asked to publicly commit not to challenge, because they did not deserve to have their loyalty questioned.

10 Coalition MPs would support spill motion

The ABC has phoned dozens of Coalition MPs and can identify 10 who would support a spill motion, while another 20 could be described as highly disaffected or harbouring deep concerns.

Earlier on Wednesday a spokesperson for Mr Turnbull denied the Communications Minister had been canvassing backbenchers for support in a potential vote.

However, the spokesperson told the ABC the former leader had taken calls and made calls to concerned colleagues.

Cabinet minister Christopher Pyne said he had been assured that was the case.

“I can tell you categorically that Malcolm Turnbull has not been ringing colleagues and canvassing for support because I asked him myself point-blank and he told me that was not true,” he told Macquarie Radio.

Julie Bishop and Malcolm Turnbull have both denied seeking to challenge the PM. Photo: AAP

On Tuesday, Ms Bishop told Cabinet she would not challenge Mr Abbott and was not “campaigning” for the job. She reiterated her stance on Wednesday.

Cabinet ministers locked in behind Mr Abbott as they wound up a two-day meeting in Canberra ahead of Parliament’s return next week.

Senior minister Ian Macfarlane said Mr Abbott’s leadership should not be opened to a vote.

“I do not think there should be a spill,” he said. “I think it’s ridiculous. We need to get on with the job at hand.”

Cabinet colleague Eric Abetz added his voice to the support for the Prime Minister.

“There’s been a whole lot of hyperventilation over nothing,” he said.

“The Prime Minister has the overwhelming support of the party room, unanimous support of the Cabinet, and we’ll continue to do what we need to do and that is look after the interests of the Australian people.”

Some Coalition backbenchers who are critical of Mr Abbott want the leadership issue resolved through a ballot in next Tuesday’s partyroom meeting.

-ABC