Barnaby Joyce will challenge Michael McCormack for the leadership of the Nationals when a party room spill is called on Tuesday, saying he has learned from his past mistakes and is the best person to lead the party to the next election.

The former leader’s tilt at a comeback won support from the cabinet minister Matt Canavan on Monday night, with the Queensland senator resigning his position to back Joyce in the leadership ballot.

Joyce phoned McCormack on Monday afternoon to inform him that there would be a spill of the leader’s position when MPs meet in Canberra for the first day of the parliamentary year, saying the party was under threat from “all sides” and the party risked being left in “the shadow” of the Liberals.

“We have to speak with our own voice, we have to drive agendas,” Joyce said.

“I want to work with my colleagues to make sure we give ourselves the very best chance to thrive and survive as a political party because that is the best thing for Australian democracy,” he said.

“It is a tough game at the moment; we are being attacked on all sides, whether it’s Shooters and Fishers, One Nation, whether it’s independents, we have to speak with our own voice in an honest and forthright way because that is actually how we will keep a Coalition government.”

While saying he was not a “perfect, cardboard cutout” without flaws, Joyce said that he had spent the past two years reflecting on how he could “do the job better” after he quit his position following revelations he was expecting a baby with his former staffer, Vikki Campion.

He said he had decided to run after “reflecting on the concerns that people have brought to my attention”, in reference to internal grumblings about McCormack’s performance.

“We’ve got to make sure that we are not a shadow of another party, that we speak with our own voice,” he said.

Joyce would not speculate on how the numbers of the 21-member Nationals partyroom would divide on Tuesday, with sources saying the count was too close to call, with both McCormack and Joyce lobbying colleagues for their support late on Monday.

The Queensland MP Llew O’Brien, a strong internal critic of both McCormack and the outgoing deputy Bridget McKenzie, will move the spill motion, and it is expected to be seconded by either George Christensen, David Gillespie or Canavan.

The leadership position is decided by a secret ballot, with MPs due to meet at 9am on Tuesday. A result should be known by 10.30am.

Late on Monday, Canavan said he would support Joyce because the party needed to “fight a bit harder” and “shout a bit louder”.

“I do think a change of direction here will allow us to do that better for our constituents,” Canavan said.

Explaining his decision, Canavan said that regional Australians had “struggled to get our voice heard” and the Nationals needed to stop “city-based commentators” dominating debates affecting regional constituents, such as the future of coal.

Canavan said he would not stand for deputy, and it would be up to McCormack and Scott Morrison if he could return to the ministry in the event Joyce was unsuccessful.

Nationals MPs will also vote on a replacement for McKenzie as deputy, with several MPs expected to run, including the New South Wales MP David Gillespie, the drought minister, David Littleproud, and the Queensland MP Keith Pitt.

The position will be decided by a series of ballots that eliminate one unsuccessful nominee each round.

After declaring there was “no vacancy” for his position, McCormack insisted he maintained the support of his colleagues.

“I have the overwhelming majority support in the party room and of course I’m going to continue as the Nationals party leader as my colleagues want and, I think, as regional Australians expect,” he said.

“I have delivered for rural and regional Australia.”

The Victorian Nationals MP Darren Chester said McCormack had the “overwhelming support” of the party room and was doing a good job “delivering for regional Australians”.

“What’s damaging is any second, minute, hour, day the National party talks about itself and doesn’t talk about the issues affecting regional Australians,” Chester told the ABC.

The Nationals federal president, Larry Anthony, told ABC that the bout of instability in the junior coalition partner was “democracy in action”.

He also acknowledged that there was “discontent” in regional Australia about the government’s response to the summer bushfire season which had been directed to Canberra.

“I think it’s been a very difficult summer. Out in regional Australia a lot of people are hurting. A lot of it, it’s not caused by us, it’s the forces of nature, but naturally, you know, they’re looking to Canberra.”

He also said he would support whoever was successful in Tuesday’s ballot.

While announcing his support for Joyce, Canavan also revealed that he had failed to disclose he is a regional supporter of the North Queensland Cowboys, entitled to a membership of its leagues club. In November the Northern Australia Infrastructure Facility (Naif) gave a loan to the North Queensland Cowboys Football club.

Canavan claimed the undisclosed interest – which he only recalled in the last week – did not constitute a breach of ministerial standards because he had “no influence or control” over which projects Naif decided to fund, only a power to reject loans. He said he had sought advice from the prime minister’s office about the issue.

The club was granted a $20m loan under the Naif for a community, training and high performance centre next to its stadium in Townsville, on top of a $15m grant extended in March 2019.

In November the Cowboys noted that the Naif investment decision “is subject to the minister for northern Australia, Matt Canavan’s legislative consideration period and the finalisation of the Queensland Government’s consideration of the project”.

When the $15m grant was announced in March, Canavan was quoted boasting that the “investment will mean Townsville has world class facilities for multiple sports” in addition to rugby league.

When asked about the Nationals leadership spill, the Liberal minister Simon Birmingham said McCormack was “an outstanding leader” who had been a strong advocate for regional Australia.