by Phillip Coorey

National Party executives from across Australia are holding urgent talks in a bid to resolve the crisis caused by Barnaby Joyce.

The Australian Financial Review understands party executives from Queensland, NSW, Victoria Western Australia as well as the federal body are scheduled to hold a phone hook-up late Monday.

It comes amid a growing and persistent view that Mr Joyce's leadership is untenable in the wake of revelations of his extra-marital affair.

One source said there was a view that the issue needed to be resolved one way or another, and before Monday next week when the Nationals party room is scheduled to meet.

One party official, speaking on condition of anonymity, said Mr Joyce's only hope to prolong his political career was to resign from the ministry and the leadership and go to the backbench. He said this was the prevailing view among the rank and file.

The meeting was called as Nationals MP and heir apparent Michael McCormack repeatedly declined to endorse Mr Joyce nor rule out a move against him when Parliament returns next week.

In an awkward interview with Sky News on Monday, Mr McCormack who is Minister for Veterans Affairs, struggled to give a straight answer when asked at least eight times whether he supported Mr Joyce.

"Barnaby Joyce at the moment enjoys the support of the National Party," he said.

"Barnaby Joyce will continue to be the leader as long as he's got the support of the National Party room."

A significant number of Nationals MPs believe Mr Joyce must quit as leader and if he survives until Monday next week, the matter will come to a head at the scheduled party room meeting.

Asked on Sky News whether there have been discussions about replacing Mr Joyce, Mr McCormack said "there's been talk about what may or may not happen but, at the moment Barnaby Joyce is the leader of the National Party."

Lucy reaches out

Earlier Monday, Prime Minster Malcolm Turnbull revealed Australia's first lady, Lucy Turnbull, had phoned Mr Joyce's wife Natalie to offer comfort in the wake of revelations of her husband's extramarital affair.

With the latest Newspoll showing two-thirds of voters believe Mr Joyce should step down as Nationals leader but Mr Turnbull's approval rating also falling, Mr Turnbull told radio 3AW his wife Lucy has contacted Natalie Joyce but he would not be doing so.

"I know Lucy had contacted her. Luce reached out, as have a lot of people."

Relations between Mr Turnbull and Mr Joyce plummeted Friday after Mr Joyce labelled the Prime Minister's denunciation of his behaviour as inept, harmful and unnecessary.

The pair met in Sydney on Saturday to smoke the peace pipe and, should Mr Joyce survive as leader, Mr Turnbull said again Monday they could continue to work together as Prime Minister and Deputy Prime Minister.

"We have to be very professional about the relationship and get on with it. There is not an issue or conflict between the Liberal Party and the National Party," Mr Turnbull said.

But Mr Turnbull made no apology for his strong comments on Thursday in which he described Mr Joyce's behaviour as a shocking error of judgment, urged him to consider his options and banned sex between ministers and their staff.

"It was very important for me on Thursday to speak from the heart, to speak frankly about what had happened, and most importantly to demonstrate to Australians that I was going to do everything I can to ensure it doesn't happen again," he said.

Bishop declines to back ban

On the weekend, former prime minister Tony Abbott criticised the sex ban and on Monday, deputy leader Julie Bishop, who had previously criticised the idea when proposed by an independent MP, also declined to endorse it.

"There are still areas of a politician's life that are and should be private," Ms Bishop told Sky News.

"What the prime minister is seeking to do is ensure that there are not relationships within ministers' offices that can lead to an improper influence over a minister's decisions to conflicts of interest, to misuse of taxpayers funds."

Asked directly if she supported the ban, she said: "I will abide by the ministerial code of conduct."

Labor leader Bill Shorten ended days of uncertainty and said he would maintain the ban if he became prime minister.

The Newspoll published in The Australian shows the Coalition trailing Labor by 53 per cent to 47 per cent on a two-party preferred basis. It's the 27th consecutive Newspoll in which the Coalition has trailed Labor. Mr Turnbull cited 30 negative Newspolls as a reason for rolling Tony Abbott.

The poll showed 65 per cent thought Mr Joyce should quit as Nationals leader, 64 per cent supported the sex ban, while Mr Turnbull's preferred prime minister rating fell 5 percentage points to 40 per cent and Bill Shorten's rose 2 points to 33 per cent.

Mr Joyce has lost significant support in his own party with several sources saying the majority wants him gone. He is on leave for the week and next Monday's party room meeting looms as crunch time.

There was a further headache for Mr Turnbull courtesy of the Nationals when renegade MP George Christensen posted a picture of himself on social media holding a gun and advocating violence against the Greens.

Greens leader Richard Di Natale has asked the Australian Federal Police to investigate. Mr Turnbull called the behaviour inappropriate.