Barnaby Joyce will take leave next week, as pressure grows over his affair with a former staffer and senators vote for him to resign or be sacked for breaching ministerial standards.

Key points: PM announced Mathias Cormann will be acting PM next week instead of Mr Joyce, who will take leave

PM announced Mathias Cormann will be acting PM next week instead of Mr Joyce, who will take leave A vote in the Senate calling for the Deputy PM to step down passed 35-29

A vote in the Senate calling for the Deputy PM to step down passed 35-29 Nationals senator Barry O'Sullivan used parliamentary privilege to level accusations at other MPs

Malcolm Turnbull announced in Question Time that Finance Minister Mathias Cormann would instead be acting PM when the Prime Minister leaves the country.

Mr Joyce issued a statement saying he would be on leave next week and had advised the PM he wanted to support his family and partner after such intense public focus on personal matters.

Mr Joyce has been under immense pressure because of his affair with former staffer Vikki Campion and questions about whether the code of ministerial conduct was followed.

The Senate has compounded that, with Greens, Labor, Derryn Hinch and the Nick Xenophon Team voting for a motion asking the Deputy Prime Minister to step down for breaching ministerial standards.

His future is precarious, with some of his colleagues considering asking him to quit as leader because of the damage the revelations about his relationship have done to the party.

Shortly after the PM announced Mr Joyce's leave arrangements, Nationals senator Barry O'Sullivan used parliamentary privilege to level accusations at other MPs.

Sorry, this video has expired Barry O'Sullivan levels accusations in the Senate

In the Senate, he said Greens senator Nick McKim and Labor MP Tony Burke had their own questions to answer, and questioned Greens senator Sarah Hanson-Young's travel expenses.

"I'm asking Senator McKim: does he want to talk about office relationships and the conflicts that come with it while you're a member of parliament? That's what I'm asking," Senator O'Sullivan said.

"Tony Burke, not one word.

"Senator Hanson-Young, with a family on a whale-watch trip, thousands of dollars at a cost.

"Their hypocrisy knows no boundary."

The ABC has contacted the offices of Senator McKim, Senator Hanson-Young and Mr Burke for responses.

Labor questions if leave signals Joyce cannot do his job

The prospect of Mr Joyce being acting prime minister when Mr Turnbull travelled overseas next week had been worrying many Nationals.

They feared that being in the spotlight would have added to the crisis.

Mr Turnbull has now defused that by announcing Mr Joyce will be on leave instead of being acting PM.

Sorry, this video has expired The PM announced in Question Time Barnaby Joyce would be taking leave.

Labor has already questioned if that decision means Mr Joyce cannot do his job.

"Are we simply meant to believe it is all a big coincidence?" Labor leader Bill Shorten asked.

Deputy Liberal leader Julie Bishop would normally be the acting Prime Minister if the Nationals leader is unavailable.

But Ms Bishop is also travelling overseas next week, which is why Senator Cormann will take the job.

He is next in line because of his role as Government Senate leader.

Labor continues attack over rent-free apartment

Mr Joyce remains under intense pressure, with Federal Labor demanding to know if he misled Parliament earlier today over the rent-free use of an apartment.

The Opposition accused Mr Joyce of breaching ministerial standards by asking for a place to live and receiving the gift of six months' free rent, which is worth about $12,000.

Labor argued the code means ministers "must not seek or encourage any form of gift in their personal capacity".

Mr Joyce insisted he had not breached the code because he said he did not ask his friend, businessman Greg Maguire, for the apartment, arguing that Mr Maguire offered it to him.

Sorry, this video has expired Barnaby Joyce told Parliament he was approached by a friend with the accommodation offer.

But Labor has now questioned whether or not Mr Joyce misled Parliament, because two journalists who previously interviewed Mr Maguire quoted him as saying Mr Joyce did ask for the use of the premises.

In January, Mr Joyce updated his parliamentary register to show that he had been given free use of an apartment in Armidale, but did not reveal that it was donated by Mr Maguire.

In Question Time today, Labor also attacked Mr Joyce over his relationship with Mr Maguire.

It pointed out that Mr Joyce hosted a function organised by his department at Mr Maguire's Powerhouse Hotel in Tamworth.

Labor said the function cost $5,000.

Mr Joyce took the questions on notice.

The Agriculture Minister David Littleproud later responded that the Department selected the Powerhouse Hotel for the event in line with procurement guidelines.