Respected NSW senator Arthur Sinodinos has launched an extraordinary attack on his former ministerial colleagues for leaking against Treasurer Joe Hockey, calling on Prime Minister Tony Abbott to sack anyone found guilty of destabilising the government.

And Social Services Minister Scott Morrison says he "wouldn't have a clue" which cabinet ministers are briefing against the man he could replace as Treasurer.

Mr Morrison also dismissed suggestions a reshuffle could take place if the Canning byelection goes badly for the Coalition, describing such a move as "speculative nonsense".

In a rare statement on Monday, Senator Sinodinos said that ministers "should be working hard to win the Canning byelection rather than back grounding against a colleague to scapegoat a potential loss".

"Holding out the prospect of a reshuffle and even a double dissolution election smacks of defeatism and a lack of focus on the substantive issues of governing," he said.

"The Prime Minister should sack any minister or adviser who is engaged in such deliberate leaking and destabilisation. We should be working to achieve a swing to us in this by-election.

"Mr Shorten is the real enemy, not fellow Liberals."

Senator Sinodinos was chief of staff to former prime minister John Howard, and voted in favour of the spill motion against Mr Abbott in February.

Two cabinet ministers have told Fairfax Media that Mr Abbott is being urged to dump Mr Hockey, while an early federal election, to be held in March next year, is also being discussed at the highest levels of the Abbott government.

The move to sacrifice the Treasurer would designed to shore up Mr Abbott's own leadership and quell a potential backlash after the September 19 poll.

The Liberal Party holds the seat of Canning with a margin of 11.8 per cent but recent polling in the seat shows it is now on a knife edge, with swings to Labor of as much as 10 per cent forecast.

Cabinet ministers have told Fairfax Media that a swing of more than six per cent against the Coalition - which would still see the Liberal Party's candidate Andrew Hastie win the seat -€“ would be bad news for Mr Abbott and more than 10 per cent would be "dire".

Mr Morrison told Fairfax radio station 2GB on Monday that Mr Hockey was a great bloke who was doing a tremendous job.

"We are all focused on the issues of jobs, growth and community safety," he said.

"These stories are better placed in Who magazine, not in a serious newspaper."

Foreign Minister Julie Bishop, meanwhile, said that "instead of criticising Joe Hockey, people should recognise the enormous task he has in repairing the budget that was so trashed by Labor in its six years in office".

Asked about the prospect of an early election, Ms Bishop said didn't believe such a move was being considered but did not rule it out.

Former Liberal Leader John Hewson said the leak suggested MPs were positioning should the Canning byelection go badly and warned: "There's a risk that Canning will go worse than they presently expect."

"You could imagine them coming from those who aspire to the position and those who want to protect Abbott," he said.

Dr Hewson did not express a view on whether Mr Hockey should remain Treasurer, but said "a lot of people in the broader community, business people and so on" had publicly criticised his performance since his first budget.

"My view is he's rusted on to Abbott and vice versa," he said.

"I don't think Abbott would easily make that decision unless it was to preserve his own position...the amazing thing is he [Mr Hockey] hasn't been able to get the economy on the front page. All the turmoil of the last few weeks, changes in world markets and all these things you'd expect it would be front and centre."

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