Deputy Nationals leader David Littleproud has confirmed he will try to topple Barnaby Joyce as leader when the party meets in Canberra on Monday.
Mr Littleproud, who was agriculture minister in the Coalition government and is the Member for Maranoa in Queensland, said in a statement: "This afternoon I advised Barnaby Joyce of my intention to nominate for the position of Leader of The Nationals.
"I also took the opportunity to thank him for all his service to our party.
"Ultimately, this is a decision on who will lead the Nationals to the 2025 election. Therefore, out of respect to my colleagues, I will be making no further public statements until after the meeting on Monday."
The challenge follows Gippsland MP Darren Chester's announcement he would also challenge Mr Joyce, arguing "extreme" comments from colleagues on climate change and the Coalition's net zero policy had contributed to the loss of once-safe Liberal seats in cities.
But Mr Chester has played down his chances of winning the leadership ballot.
Former Nationals leader Michael McCormack, who was rolled by Mr Joyce last year, had also been considering putting his hand up.
The ABC has spoken to nine Nationals who privately said they would vote for Mr Littleproud in a leadership ballot, while others remain undecided or will support Mr Joyce.
While the cities voted for change at the federal election, rural and regional areas did not.
The Nationals held all 16 of their Lower House seats but there were swings against them in most areas, despite the party having billions of dollars in regional infrastructure announcements.
In the aftermath of the election, the Nationals have shown they are again divided on climate change and net zero, and some argue a new leader is required to unite the party in opposition.
Since 2017, Mr Joyce has resigned twice as leader, once because of dual citizenship and a second time due to a sexual harassment allegation.
He unsuccessfully challenged his successor Mr McCormack in 2020 but eventually rolled him last year when the Coalition was stuck in protracted negotiations over its net zero target.
Mr Littleproud has been one of the party's stronger advocates for action on climate change and established a biodiversity stewardship program while in government.
