David Littleproud will run against Barnaby Joyce for leadership of the National Party.
The high-profile deputy leader announced on Saturday he'd told Mr Joyce of his decision to nominate.
"I also took the opportunity to thank him for all his service to our party," Mr Littleproud said.
"I feel this is the appropriate time to put myself forward for my party room's consideration as their leader.
"Ultimately, this is a decision on who will lead The Nationals to the 2025 election."
It is now a three-man race between Mr Littleproud, former deputy prime minister Mr Joyce and former veterans affairs minister Darren Chester.
Mr Chester confirmed his nomination on Friday, pitching a fresh start for the party.
"Australians want a calmer, moderate and more respectful political debate which is focused on policies, not personalities," he said in a statement on Facebook.
The junior coalition partner will have its first post-election meeting on Monday where they will spill the leadership as per tradition.
Outgoing and surviving Liberals have blamed Mr Joyce for part of the coalition's poor showing last Saturday, on top of the negativity surrounding Scott Morrison.
Former deputy prime minister Michael McCormack may also put his hat in the ring for the party's top job, having been critical of Mr Joyce's leadership since he lost in a leadership spill against him in 2021.
Anne Webster will contest for the deputy leadership role, currently held by Mr Littleproud.
Australian Associated Press