The prime minister is being urged to ask his deputy to stand down, as the fallout from Barnaby Joyce’s affair with a former staffer threatens the stability of the Turnbull government.

Government sources have told 9NEWS that Mr Joyce’s position is untenable and “he should go”.

But one Cabinet minister warned that any move against Mr Joyce would be political suicide, given the government holds power by a single seat in the Lower House.

“The PM can’t dump Barnaby,” the minister said.

Mr Joyce is currently living with Ms Campion in Armidale, New South Wales. (AAP)

Vikki Campion is expecting a baby with Mr Joyce.

“That would be the end of the government.”

The prime minister cannot sack his deputy and asking him to resign could fracture the Coalition.

The Coalition is two parties – Liberal and National – and an agreement between them automatically makes the leader of the Nationals the deputy prime minister.

Only the National Party can force its leader out, something the party has only done once in its 90-year history.

Malcolm Turnbull is being urged to ask for Barnaby Joyce's resignation. (AAP)

Nationals told 9NEWS they expected Mr Joyce to stay on, although one asked about the affair with former staffer Vikki Campion said it was “probably not survivable”.

Mr Joyce will front his restive party room tomorrow morning but the Minister for Veterans’ Affairs Michael McCormack said he believed the matter would “resolve itself”.

“Barnaby will continue as the National Party Leader and we'll all get over this and move on,” he said.

Publication of the consensual relationship between Ms Campion and Mr Joyce, and the breakdown of his marriage, is unusual in Australian political reporting and it could mark the beginning of a politicised morality war.

Labor has weighed into the fray, with deputy leader Tanya Plibersek saying that the prime minister and his deputy had questions to answer over the expenditure of public money.

Ms Campion was promoted into a new position created in Senator Matt Canavan's office in April last year.

When he fell to the citizenship fiasco Ms Campion was moved to the office of the Nationals' whip, Damian Drum.

“The only interest that we have and we will keep asking questions about it is in this area of how taxpayers’ funds have been expended,” Ms Plibersek said.

“And it might be that there is no case to answer here but the Deputy Prime Minister and the Prime Minister should be prepared to answer questions about taxpayers’ money.”

That prompted the foreign minister to fire a warning shot at the Opposition.

“People in glass houses…,” Julie Bishop said.

Queensland Liberal National MP Michelle Landry put it more bluntly.