David Littleproud will face a challenge for the leadership of the Nationals when parliament resumes.
Backbench MP Colin Boyce, who represents the Queensland electorate of Flynn, said he would launch a spill motion against Mr Littleproud in the coming week.
The move, announced on Wednesday, followed the Nationals walking away from their coalition partnership with the Liberals over hate-speech laws.
Mr Boyce will run for the leadership of the party at a meeting due to take place on Monday.
He said the coalition needed to reunite.
“The reality is, (if) they follow the course they’re on now, we are going over the political cliff,” he told Sky News.