The deputy prime minister will take over the top job when Prime Minister Malcolm Turnbull flies to the United States to meet with U.S. president Donald Trump.
Speaking on the Today show on Monday, Political Editor Chris Uhlmann said there was "growing discontent" in the National Party, with party elders believing Mr Joyce was doing irreparable brand damage.
Ahead of the Nationals party meeting, the deputy prime minister's New South Wales Nationals colleague John Williams said he did not know if Joyce would lead the party to the next election.
This week it was revealed Mr Joyce, 50, and Ms Campion are in a private relationship and are expecting a baby.
'Not the affair itself, that's nobody's business.
The spokesman said the deputy prime minister was still married when Ms Campion's appointments were made.
"I just think the sun is setting on his career, and I can't see how he can survive". Seriously, this stuff has to stack up before you start reporting it, ' he said.
Mr Joyce is now living with Ms Campion in Armidale, New South Wales, following the breakdown of his marriage of 24 years last year.
'I think his career is over, maybe not in the short term, but certainly in the medium term, ' she told the program.
The media commentator also revealed a lot more Freedom of Information requests have been lodged.
The pair were also revealed to be living together rent-free in an Armidale townhouse gifted by the deputy prime minister's multi-millionaire friend.
'It's a private matter, it's a tough matter and I don't have any more to say about it'.
Barnaby Joyce with his wife Natalie in June 2017.
The report comes a day after it emerged a second parliamentary job was created for Ms Campion after the first role was lost following Mr Canavan's resignation.
Mr Drum's taxpayer-funded staffing allocation was reportedly boosted to accommodate Ms Campion.
Campion is now pregnant, and had been involved with Joyce since past year.
A spokesman for the Prime Minister said Mr Joyce had not breached ministerial standards in regard to the employment of partners because Ms Campion was not the deputy prime minister's "partner" at the time of her appointments to the offices of Matt Canavan and Mr Drum.
He said the government needed to clarify the situation.
Mr Joyce's marital breakdown became public knowledge late a year ago when he returned to Parliament as Deputy Prime Minister.
Mr Canavan issued a statement claiming Ms Campion was "suitably qualified" for the role for which she was hired.
Malcolm Turnbull said he still had confidence in Barnaby Joyce.