A Greens push to force motorists to leave a minimum passing distance for cyclists looks set to fail in the Victorian Parliament, after getting lukewarm support from the major parties.

A bill being introduced by the Greens in the Upper House would force motorists to remain at least a metre away from cyclists when they are passing on the roads.

The Greens introduced the bill last year, but it lapsed because of the November state election.

The current law requires drivers to give "sufficient" space when passing a cyclist but does not specify what that distance is.

The death of Italian man Alberto Paulon in a car-dooring incident on Sydney Road in Brunswick last month and a number of other cyclist deaths have sparked debate about how the roads can be better shared.

Opposition leader calls plan 'typical thought bubble'

Roads Minister Luke Donnellan indicated the Government favoured maintaining the status quo.

Premier Daniel Andrews said he would not commit to supporting the Greens' bill, but welcomed the debate

"We have to have a debate and a discussion about the best way to keep all road users safe and perhaps change the culture to make people understand we share the roadway," he said.

"I think there are many challenges with that and important work is never easy and I think it's important we do everything we can."

Opposition Leader Matthew Guy said the Coalition was unlikely to support the bill.

"I'm just not sure how it's going to work," he said.

"How would you penalise people in a car for being too close to a bike if the bike pulls up next to the car?

"It just seems like a typical idea from the Greens that's been thought out in a thought bubble."

Melbourne Lord Mayor Robert Doyle also had concerns about enforcement.

"I think of the top of the city as you come across Spring St into Collins St, you could not have a metre separation there. It's just physically impossible," he told 774 ABC Melbourne.

Greens MP Samantha Dunn said police were well-equipped to make determinations on how the rules would be applied.

"All of those things are going to be subject to police investigation," she said.

"We don't want drivers going past cyclists at 20 centimetres, that's just way too close and they are just too vulnerable."

Similar laws are in place in Queensland, South Australia and the ACT and are being considered in Western Australia.