Two key Victorian upper house crossbenchers have flagged that they will not support the state government’s rental-reform package unless concerns over pets are addressed.

The bill, due for debate on Tuesday, proposes allowing tenants the automatic right to pets in all rentals unless landlords can prove their property is unsuitable – a sore-spot with property owners and real estate agents.

Other proposed changes to the rental rules include inalienable minimum standards, changes which would make it easier for renters in family violence situations, and prescribed modifications that do not require prior approval from landlords – modifications to be determined by the government at a later date.

Despite grumbles about the timing of the bill’s introduction to Parliament, the Greens are expected to pass the bill as is. With their five votes, the Andrews government would need to secure two more to ensure the bill’s passage before the election.

Shooters and Fishers Party MPs Daniel Young and Jeff Bourman say they have have concerns about what constitutes “reasonable modifications” and want the government to be up front.

But pets could be the big deal breaker — Mr Young said the pair would only vote for the bill if the provisions were dropped, or if the government changed the legislation.

“It’s quite a complicated one. It’s not that we don’t like the in-principle argument with it,” he said. “There’s not a lot of detail around stuff that will have to be regulated.

“If someone was to put up an amendment to remove [or edit] those sections … we could be supporting parts of the bill, we could be supporting all of the bill.

“We can’t give an answer, we’re working on it.”

The Reason Party’s Fiona Patten could be the government’s best bet, but she has not been entirely enthusiastic.

“I’ve had hundreds of emails supporting the bill and few opposing it,” she said. “It doesn’t really specify what we mean by ‘small improvements’ and that sort of thing.

“And I have some sympathy in regards to pets because I’m allergic to most animals, so if someone had a pet and I was the landlord, it would be difficult for me to go back to the property.”

Ms Patten is not yet ready to commit, but hopes the bill will be dealt with by the end of the week or before the election.

Vote 1 Local Jobs MP James Purcell, is also yet to make a decision, and feared the changes could be damaging to the rental market, because it would make life too hard for landlords – but he said he was still open to voting in favour.

“People who buy and rent properties need to have some rights over who they rent to,” he said.

Independent crossbencher Rachel Carling-Jenkins did not respond to requests for comment.

The Greens, committed to passing the bill before the election, plan to fight to keep pet provisions.

“We protested on the steps of Parliament to prompt Labor to finally take action,” Northcote MP Lidia Thorpe said. “We were joined by several renters and their pets who want peace of mind they won’t be separated whenever they move. This is a crucial part of the legislation that has the Greens’ full support.”

Ms Thorpe would not be drawn on whether the Greens’ support was conditional on the new pet rules remaining in the legislation. If the five Greens pull their support, it is unlikely the bill will pass.

There are just six sitting days left for this Parliamentary term. Ms Patten was concerned the opposition would do their best to filibuster the debate, and indefinitely suspend the vote for the bill. She floated the idea of extending sitting hours and adding extra sitting days to ensure the bill was passed before the election.

“Frankly I’m fed up with the time-wasting for political purposes we’ve been seeing these weeks,” said Ms Patten. “If the government were keen to extend sitting times this week to get this through, I’d support that.”

Mr Purcell and the Shooters, Fishers and Farmers were also open to extending sitting times, but only if they felt the Opposition was unfairly delaying the debate.