Retailers say it will be difficult to make plastic bags disappear completely, despite the Greens pledging to phase them out.
The Greens want to ban single-use plastic bags by 2020, charging a 20c levy in the meantime with 15 cents going to community groups for environmental clean-ups and the rest for research and development into alternatives.
But Retail NZ spokesman Greg Harford says it won't be a straight-forward mission.
"There's certainly already alternatives available. Ultimately it's going to come down to consumer demand, and whether consumers are ready to relinquish those bags entirely inside the next three years."
The retail advocacy group believes a plans to ban single use plastic bags will inadvertently create other environmental issues.
"Typically bin liners that you might buy from the supermarket are heavier-grade plastic bags you might get at the checkout. They actually have a larger environmental footprint."
The Greens want New Zealand to commit to zero waste by 2050.