Victorian Premier Daniel Andrews faces a motion of no confidence in parliament over his handling of COVID-19.
The motion is expected to be tabled in the state's lower house on Thursday.
"I will be moving a motion of no confidence in this premier. Victorians have had enough," Opposition Leader Michael O'Brien said.
The premier brusquely dismissed the move when asked in his daily media conference.
"Cheap politics is no vaccine against this virus, and that is all I will say about him and that," Mr Andrews said.
Victoria has been hard hit by coronavirus, leading the nation's case numbers and on Thursday recording another eight deaths, for a total of 745 since the pandemic began.
Most of the deaths can be linked to Victoria's bungled hotel quarantine system, which is under investigation.
Strict lockdown measures designed to stem the spread of the virus have resulted in business closures and job losses.
"This is a government that has proven itself to be incompetent, dishonest and with no vision or hope for Victorians," Liberal-Nationals leader Mr O'Brien said.
"By moving a motion of no confidence, every member of the legislative assembly will have to make a decision - are they going to vote to protect Daniel Andrews' job? Or are they going to vote to protect Victorians' jobs?"
Labor has a clear majority in the lower house and Mr O'Brien's motion is not expected to pass.
It will be tabled on Thursday and debated next month.