The Labour Party is considering withdrawing its support for legislation reforming food safety standards, which would end cross-party support for the bill and weaken its chances of becoming law.
But the Food Bill is still likely to be passed because National needs only two more votes from its support partners to get the measure through its second and third readings.
The bill would set up a risk-based food safety framework that would replace 30-year-old legislation, but it has been criticised for its potential effect on community growers and small-scale food traders.
It was reported back from a select committee more than a year ago with broad support, but Green MP Steffan Browning has since said he will push for further amendments to exempt small traders from having to comply with unnecessary red tape. He also said the proposed powers for food safety officers were excessive, including giving them immunity from civil and criminal liability.
Mr Browning could not say if the Green Party's ongoing support for the bill was conditional on further changes because he had not had a chance to discuss it with the caucus.
The legislation previously had the support of both major parties, but yesterday, Labour's backing looked shaky.
"We will not be giving our support to this bill unless a number of areas are clarified, including areas affecting small growers," primary industries spokesman Damien O'Connor said.
"We do not want to see New Zealand end up with some unwieldy piece of legislation that confuses the retailers and those working in this area, particularly those working in volunteer or community settings."
The Government has given assurances that the bill would not affect those growing their own food and swapping it with friends and neighbours.
But doubt remains over whether some low-risk groups would need to be exempted from the red tape of registering with a national safety plan. Such groups include those that swap community food, or trade foods not straight out of the garden, such as jams, preserves and baking.
Concerns have also been raised by small businesses which fear that the compliance costs could push them under.
This week, Aucklander Jenine Abarbanel, a member of food network Ooooby (Out of Our Own Back Yards), wrote to Food Safety Minister Kate Wilkinson with her concerns.
"For many rural (and some suburban) people, roadside stands, farmers' markets and similar outlets are their best source of reasonably priced fresh produce," her letter said.
"If these small producers are forced to jump regulatory hurdles, or pay fees related to this trade, there will be strong incentive for them to stop this activity entirely."By Derek Cheng Email Derek