Renters say a housing warrant of fitness would give teeth to existing laws, which set standards but are largely ignored by landlords.
The Green Party is calling for rentals to be checked every three months, and landlords who fail to keep their properties up to standard be banned from renting them out.
Renters United spokeswoman Anna Mooney says last year's Healthy Homes initiative was only a start.
"The current proposal is leaving enforcement of these standards to the tenant, and that's likely going to mean low levels of compliance," she told Newshub. "A lot of renters aren't actually going to feel the benefit."
The National Party opposes the idea, saying it'll see fewer homes available for rent.
"Do they think that removing more rental [houses] from the market won't lead to more people living in cars, sheds or even tents?" spokeswoman Judith Collins tweeted.
She said it was a policy "made in a vacuum away from reality", and that National's changes before losing last year's election ensured renters were living in "warmer, drier and safer homes".
"The Government is just really starting to recognise and take seriously that there is a massive power imbalance between renters and landlords," said Ms Mooney.
Renters United estimates the cost of a warrant will be $250.
"As long as a landlord's rental property is at an adequate standard, it won't be very costly for them at all."
There are nearly 9000 eligible people waiting for a Housing NZ place to live in.
More Kiwis are renting than ever before, with home ownership rates falling over the past 30 years.