Under-fire Barnaby Joyce is preparing to be acting prime minister next week after surviving pressure from within his party to quit his job.

The deputy prime minister's relationship with his pregnant partner Vikki Campion raised concerns about the potential misuse of taxpayer funds after she was shuffled around jobs in other senior MPs' offices.

A rent-free townhouse provided to him by a businessman friend also became the subject of Labor questions in parliament on Wednesday.

Malcolm Turnbull and senior Nationals expressed confidence in Mr Joyce, despite a handful of Nationals MPs agitating for him to consider his future.

Mr Turnbull reaffirmed his deputy would act for him while he visited the White House next week.

Nationals deputy leader Bridget McKenzie was effusive when asked about the leader's future.

"I'll give you my solid, rolled-gold guarantee here that come tomorrow, come Friday, Barnaby Joyce will be leading the National party," she told Sky News.

When asked if Mr Joyce's actions passed "the pub test", Senator McKenzie replied: "There's a lot of people in the pubs who actually understand."

Cabinet minister David Littleproud, promoted by Mr Joyce in a ministerial reshuffle, said "of course" his leader had the support of most Nationals MPs.

"There's no leadership to be resolved," he told ABC radio.

"But those that want to keep this issue lingering on need to put up or shut up and leave him alone and leave his family alone."

Ministerial colleague Michael McCormack said he had not been sounded out by colleagues about replacing Mr Joyce.

Nationals president Larry Anthony was in Canberra to deal with what he called a "very difficult time" for the party.

A group of about four or five Nationals MPs is believed to have tried to get Mr Joyce to resign, but they didn't have the numbers in the 21-member party room, while some Liberal MPs were also unhappy with Mr Joyce's week-long scandal.

Mr Joyce denied breaching the ministerial code of conduct, which says frontbenchers cannot employ close relatives or partners or get them work in other ministerial offices "without the prime minister's express approval".

He argued Ms Campion was not his partner when she worked in his and Matt Canavan's office.

Damian Drum was not a minister when she transferred to his office.

Labor also attacked Mr Joyce, who once said city-dwellers should move to Armidale because houses were cheaper there, for living rent-free for six months in an Armidale townhouse belonging to his friend, multi-millionaire businessman Greg Maguire.

Mr Joyce declared the townhouse rent on his members' interests register even though he said he did not need to do so.

The rules say gifts from family members or personal friends "in a purely personal capacity" don't need to be registered unless there appeared a conflict of interest.

Ms Campion is due to give birth in mid-April.

Mr Joyce late last year separated from his wife Natalie after 24 years of marriage.