Tony Abbott's leadership has been rocked by a political earthquake and is under imminent threat, with backbench MPs variously calling for the Prime Minister to resign, for a party room ballot next week and expressing doubt he can revive his political fortunes.

A day after Mr Abbott used a National Press Club address to dig in and signal unhappy MPs would have to blast him out of office, backbench MPs were in open revolt at the direction of his government on Tuesday night.

A spokesman for Mr Abbott told Fairfax Media his position had not changed and that he still believed removing a sitting prime minister was madness.

Liberal MP Dennis Jensen on Tuesday became the first  MP to publicly call on Mr Abbott to step aside after weeks of leadership speculation and rising panic on the government backbench about the Coalition's dire position.

Foreign Minister Julie Bishop ruled out directly challenging Mr Abbott for the leadership but has reserved the right to put up her hand if
someone else moved to force him to declare the position vacant and hold a ballot.

Fairfax Media understands Communications Minister Malcolm Turnbull has told colleagues the push for change is being driven by the backbench, not by him but he, like Ms Bishop, is talking with colleagues about the government's political woes.

Just 17 months after he was elected, Liberal MPs were hitting the phones on Tuesday night to consult their colleagues about Mr Abbott's leadership woes.

According to some internal estimates, as many as 30 MPs have indicated their desire for a leadership change, raising the chances that next week's return of parliament could see events move quickly beyond the Prime Minister's control.

Dr Jensen's intervention - which has been followed by damaging public statements from other MPs critical of Mr Abbott's leadership - prompted a senior cabinet minister, Immigration Minister Peter Dutton, to claim the Prime Minister was being "sabotaged" by colleagues.

The WA MP said he had a text message exchange on December 19 last year with Mr Abbott in which he expressed his concerns about the government's direction.

Mr Abbott replied that he had heard Dr Jensen's concerns but that "we were moving in the right direction".

However, he told Fairfax Media on Tuesday night:  "I haven't seen evidence of change".

"On 23 January I texted him and said he no longer has my support, three days before Prince Philip," Dr Jensen said.

"I believe in being up front and honest about it."

He dismissed suggestions that the criticism came because he had missed out on a promotion to the frontbench.

"If I had been a good boy and whiled away my time I would probably have been promoted, but I'm in this job to do my best for my constituents and the nation."

Mr Abbott has "not stepped up as far as the prime ministership is concerned", Dr Jensen said.

He also said he did not know how many other MPs felt the same way but "I know a number feel similarly".

"I thought it was time to strike to start things moving."

Other MPs join in criticism of Tony Abbott

Queensland Liberal National Party backbencher Warren Entsch told Fairfax Media on Tuesday night that he supported a party room ballot as soon as next week when parliament sits for the first time in 2015.

"It [the leadership] needs to be resolved," he said.

"Good luck to him [Dr Jensen], good on him, it has to be resolved one way or another when people make those sorts of comments.

"The focus has got to go back to dealing with our many challenges. I'm not discouraging him [Dr Jensen] from expressing a point of view. It needs to be resolved. And I suspect it will be, one or way another."

Mr Entsch stopped short of calling on Mr Abbott to resign, though.

Also on Tuesday night, Queensland MP Mal Brough said Mr Abbott did not have his unequivocal support.

Mr Brough attacked the government's below-inflation pay offer for Australian Defence Force members.

"When the defence forces go into action, they know their lives are on the line, but when they go to training, they also risk being maimed. They risk dying. That doesn't happen to a Centrelink staff member. That doesn't happen to someone from the ATO."

Mr Brough said it would be "arrogance in the extreme" to suggest the federal government had not contributed to the Queensland election bloodbath.

WA MP Ken Wyatt told Fairfax Media he would wait for the first party room meeting of 2015 before expressing an opinion about Mr Abbott's future as leader.

Queensland MP Bert Van Manen said: "It didn't matter who the leader is, we have to change our systems of engaging with the Australian people".

Asked if Mr Abbott could recover, Mr Van Manen said that was "a really good question. It's been a fairly rapid decline".

Former prime minister John Howard would not comment on the leadership ructions engulfing the Liberal Party or on Mr Abbott's future when contacted by Fairfax Media.

"I have no comment to make, thank you for your time," he said.

Liberal MP Karen McNamara, who holds the marginal seat of Dobell on the NSW central coast, said she agreed with Mr Entsch, saying the current instability "has to be sorted out".

"This is a distraction for people. What we should be doing is getting back to being a good government," she said.

Ms McNamara said the leadership instability made it harder for MPs like her in marginal seats. She won Dobell from disgraced former Labor MP Craig Thomson.

She would not comment when asked directly whether she supported Prime Minister Tony Abbott.

MPs could trigger leadership spill

Mr Brough's criticisms come after he confirmed to Fairfax Media on Saturday that he had approached to challenge Mr Abbott.

Mr Brough would almost certainly not be elected prime minister in any challenge but the move could pave the way for Foreign Minister Julie Bishop, Communications Minister Malcolm Turnbull or Social Services Minister Scott Morrison to seize the top job.

Ms Bishop has told Mr Abbott and her cabinet colleagues that she will not challenge for the leadership.

In a bid to end days of damaging speculation, Ms Bishop assured the Prime Minister she had not been campaigning for his job and had not phoned backbenchers seeking their support or been counting any numbers.

Ms Bishop's declaration came after Mr Abbott earlier on Tuesday refused on several occasions to confirm that he asked his deputy to promise she wouldn't run and she declined to give the pledge.

The deputy Liberal leader's commitment not to challenge does not rule her out from running if a leadership ballot is declared and all positions are open.

Tony Abbott being 'sabotaged': Dutton

Mr Dutton sprang to Mr Abbott's defence on the ABC's 7:30 program on Tuesday night and said the Prime Minister was being "sabotaged" during crucial media cycles.

"I sat in Parliament through the Rudd/Gillard/Rudd years and I don't want our party to go through that. I want the PM halfway through his first term, elected by the public, to have a fair go," he said.

"Julie Bishop, Malcolm Turnbull and Scott Morrison have been very clear in their support of the PM and I think people going out to sabotage the PM so that he can't get out a clear message just is outside the bounds of what the what Australians see as a fair go."

Asked if he would "pull the trigger" on a leadership spill if no one else would, Dr Jensen told 7:30: "Well I'd have to decide that at the time. That's pretty much a hypothetical, I don't want to sort of think about that too much at the moment."

"Obviously a spill is the obvious mechanism. Now a spill doesn't have to be with a specific challenger. When Wilson [Tuckey, a former Liberal MP] and I signed the original spill motion back in 2009 there was no nominated challenger, you may recall. Kevin Andrews stepped up a little bit later on and that obviously precipitated the chain of events that resulted in Tony Abbott becoming opposition leader."

Dr Jensen added that he didn't believe there was anything Mr Abbott could now do to save his leadership, just a day after the Prime Minister gave a major speech at the National Press Club designed to regain support and buy him some time.

Follow us on Twitter