Deputy Prime Minister Barnaby Joyce has publicly confirmed his former staffer Vikki Campion is his partner, but maintains they were not together when she worked in his office.

Key points: Mr Joyce has told the media this morning Ms Campion is "without shadow of a doubt" his partner

Mr Joyce has told the media this morning Ms Campion is "without shadow of a doubt" his partner He apologised to his wife Natalie, their daughters, Ms Campion, and voters in his electorate

He apologised to his wife Natalie, their daughters, Ms Campion, and voters in his electorate There is still speculation as to how much Malcolm Turnbull knew of the relationship

Mr Joyce made a short statement outside Parliament this morning, apologising to his family and to voters in his electorate.

"I'd like to say to Natalie how deeply sorry I am, to my girls how deeply sorry I am … [and] to Vikki Campion how deeply sorry I am that she has been dragged into this," he said.

He has followed that with a written statement which goes into more detail about his deep regret at the failure of his 24-year marriage.

Mr Joyce's statement sets out that he and his former media adviser Ms Campion are having a child together in mid-April.

He asks for privacy, saying: "This has been a searing personal experience for Natalie, our daughters and for Vikki.

"Criticise me if you wish but please have some regard for them."

Despite Mr Joyce's apology, many in the Coalition are furious with him and the distraction caused by his personal crisis.

Nationals backbencher Darren Chester, who was dropped from Cabinet in last year's reshuffle, conceded the situation was a problem.

"You would have to be a mug to suggest this is not a distraction and not a problem for us," Mr Chester said.

"When people's deeply personal lives and private matters become public knowledge and they are aired in the way they have been aired it is very disturbing."

Chatter moves to who'd replace Joyce if he stepped down

Mr Joyce's future is openly being questioned by Coalition MPs.

Nationals backbencher Ken O'Dowd said a number of his colleagues would be eager to lead the party if Mr Joyce were to step aside.

Mr Joyce has said he has no intention of quitting.

But in an interview on Radio 4CC, Mr O'Dowd said the scandal was embarrassing and many Nationals would be interested in Mr Joyce's job.

He said he was not predicting anything would happen with the leadership, but said he might put his hand up if there was an opportunity.

Labor has again tested Malcolm Turnbull's support for Mr Joyce.

When asked if he retained confidence in the deputy PM, Mr Turnbull simply said "yes".

This morning, shadow attorney-general Mark Dreyfus questioned how tenable it was for Mr Joyce to be acting Prime Minister next week when Malcolm Turnbull heads to the United States.

"Acting Prime Minister is an extraordinarily important position and it is hard to believe Mr Joyce could do justice to that position given the distractions he is now enduring," he said.

Coalition backbencher also questions Joyce acting as PM

LNP backbencher Ian Macdonald added to the pressure on Mr Joyce, saying that him being acting Prime Minister would "take the focus away from where the country is heading".

Senator Macdonald said Mr Joyce was the only person who could resolve the private issue.

When pressed on whether the Deputy PM and Nationals leader should step aside, Senator Macdonald said it was "a matter for Barnaby to determine".

"I am sure he is considering all the options," he said.

"I know he, like me, would not want to detract from the Government's commitment to govern Australia properly," he said.

Senator Macdonald said the focus on Mr Joyce was a distraction from the Government's ability to promote itself.

'Mr Turnbull has to explain what he knew'

Labor piled on the political pressure today in moving to stop Mr Turnbull from distancing himself from Mr Joyce.

"Mr Turnbull has to explain what he knew and when he knew it about the circumstances of Mr Joyce's conduct," Mr Dreyfus said.

"It goes directly to the matter of ministerial standards."

Labor has questioned whether Ms Campion's employment in other Nationals offices breached the ministerial code of conduct.

Those rules say employing a minister's partner or family member must be approved by the prime minister.

In Mr Joyce's written statement, he said he did not discuss the matters with the PM or his office because, "Vikki was not my partner".

That reasoning has been widely criticised because Centrelink is much more stringent in the way it defines relationships when it calculates benefits.

Labor frontbencher Chris Bowen said Centrelink would regard it as laughable.

Greens senator Rachel Siewert said she had received emails from people aghast at the excuse that Ms Campion was not Mr Joyce's partner.

Senator Siewert said single parents facing questions from Centrelink about their relationship status considered it a double standard.

There has been intense focus on Mr Joyce in newspapers across the nation today, touching on his personal behaviour towards women and his travel arrangements.

Finance Minister Mathias Cormann said he supported Mr Joyce as a friend and colleague.

"I can only imagine how distressing the reporting of recent days is to his wife and kids and his new partner for that matter," Senator Cormann said.

But he also again attempted to distance the Liberal Party from the Nationals, saying the leadership of the National Party is a matter for the Nationals.