Former opposition leader Matthew Guy is set to challenge Michael O'Brien for leadership of the Victorian Liberals.
AAP understands Mr Guy will make a tilt for the position during a meeting at the party's headquarters on Tuesday morning, before parliament resumes for the first time since the state's sixth coronavirus lockdown was announced.
Mr Guy and two of his key backers, Kew MP Tim Smith and Brighton MP James Newbury, resigned from their shadow ministry roles on Monday morning, ahead of the vote.
Benambra MP Bill Tilley has also resigned as Liberal Party whip in the Legislative Assembly.
"Matthew Guy would not be running if he did not have the numbers," an MP told AAP on the condition of anonymity.
Another was disappointed the spill was going ahead and said the Liberal Party should be focusing on families, school students and small businesses struggling amid the pandemic, rather than themselves.
It is understood Mr O'Brien was asked to step down but refused.
The leadership challenge comes less than six months after Mr O'Brien fended off another from Gembrook MP Brad Battin.
Mr Battin failed to garner the support of enough MPs to bring on the challenge, including a key group who want to see Mr Guy returned as opposition leader.
At the time, Mr Guy denied he was harbouring leadership ambitions.
"No, I've made that very clear," the Bulleen MP said.
The 47-year-old former opposition leader resigned after a disastrous loss in the 2018 state election.
He was replaced by Mr O'Brien, who has faced criticism for failing to land any blows on Premier Daniel Andrews and his government amid the pandemic.
For the first time, the meeting will not be held in the Liberal party room at parliament, due to coronavirus density restrictions.
The party's 31 state MPs will first need to vote to bring on a spill motion and declare the leadership vacant.
Assuming that's successful, they will then vote on who they prefer as leader.
Labor government Health Minister Martin Foley described the looming leadership spill as "irrelevant".
"The Victorian government, the Victorian community have got one focus. That is to beat this pandemic," he told reporters on Monday.
"Everything else is irrelevant."
