Barnaby Joyce has not returned a phone call to Cabinet colleague Mathias Cormann, but he did dial a journalist to let it be known he will not resign.

Key points: Acting PM Mathias Cormann couldn't get on to Barnaby Joyce today, instead left a voicemail

Acting PM Mathias Cormann couldn't get on to Barnaby Joyce today, instead left a voicemail Deputy PM spoke to a Fairfax journalist to declare his determination to remain as Nationals leader

Deputy PM spoke to a Fairfax journalist to declare his determination to remain as Nationals leader ABC understands eight Nationals want their leader to go, eight want him to say, the rest are unsure

The Deputy Prime Minister is on a week's leave to sort out his personal crisis as he deals with the fallout from his marriage ending and the pending arrival of a new baby.

In other circumstances he would have been acting prime minister from tomorrow when Malcolm Turnbull flies to the United States.

But Senator Cormann was given the honour of acting as PM instead.

He said today he had unsuccessfully tried to call Mr Joyce.

"I have left a voicemail message for him, we haven't had a chance to talk, no," Senator Cormann said.

But despite being on leave, Mr Joyce has spoken to a Fairfax journalist, declaring he is determined not to budge from the Nationals leadership.

Senior figures in the Nationals held a phone hook-up yesterday to discuss how to manage the crisis in the party.

The problems intensified when one of the ministers considered likely to be the next leader, Michael McCormack, repeatedly refused to rule out a challenge on Monday.

Mr McCormack eventually said he supported Mr Joyce, but his comments were probably enough to prompt Mr Joyce to make it known he has no intention of quitting.

Eight Nationals in the party room want Joyce gone

Prioritising the call that would send a message to his colleagues over a chat to a Liberal Cabinet colleague makes strategic sense for Mr Joyce, because Liberals — including Senator Cormann — are trying to take a hands-off approach to the Nationals problem.

"Barnaby Joyce is a good friend and valued colleague, he's an effective senior politician," Senator Cormann said.

"He's made a significant contribution in the past and I'm sure he will make a significant contribution in the future. What form that will take is matter for the National Party."

Instead of a post card from his holiday, Mr Joyce has sent a message via the front page to make it clear he has no intention of stepping down.

His colleagues are now in no doubt about that, but not all of them agree that he should stay.

About eight Nationals in the party room of 21 think he should quit the leadership, while another eight want him to keep his job. The rest are unsure.

That makes it difficult to resolve despite the increasing pressure from party elders for the Nationals to find a way to end the stand-off.

The WA Nationals publicly withdrew their support for Mr Joyce on Tuesday afternoon, with state leader Mia Davies saying he was causing "ongoing damage" to the party.

Former leader Tim Fischer told The Conversation the matter had to be resolved quickly.