Greens Leader Samantha Ratnam signalled on Monday morning that she and her colleagues were open to the idea of an arrangement with Labor, although Labor has already ruled out a deal with the emerging third party.

With the Greens targeting balance-of-power status in both houses of the State Parliament, the party’s candidates gathered there on Monday to launch their election pitch.

While announcing headline policies of free ambulance cover for all Victorians and a plan to spend hundreds of millions of dollars to maintain state schools, Ms Ratnam said she and her colleagues were out to “make history” on November 24.

With the Greens holding five upper-house seats, another three in the lower house and in a competitive position to capture two more inner-city electorates as the state prepares to vote in less than five weeks, balance-of-power status is a realistic prospect.

The Greens leader dismissed Premier Daniel Andrews' ‘'no deal'’ stance as “posturing”.

“If the people of Victoria do vote us into the balance of power, I think it would be wise of Premier Andrews to talk to The Greens,” Ms Ratnam said.

Her comments look set to sharpen attacks by the Liberals and Nationals on a possible "Greens-Labor" coalition as campaigning steps up.

Ms Ratnam would not rule out demanding ministries as a condition of support for a minority Labor government but said a deal with the Coalition was unlikely.

“It’s very hard to see us doing a deal with the Liberals, given their lurch to the right, their complete absence of climate action, no renewable energy policy,” Ms Ratnam said.

“It’s very hard to see us forming government with a party that is ... moving away from what Victoria wants.”

Opposition education spokesman Tim Smith said the Liberals had a stable, long-term coalition with their Nationals partners.

But after the November election there would be a Greens-Labor coalition that will be extreme and unpredictable, he said.

"You can't trust a Greens-Labor coalition. That would be disastrous for Victoria's economy, for Victoria's education," he said.

With Benjamin Preiss