Federated Farmers is urging New Zealand's Trade Minister, Tim Groser, to insist on the elimination of agricultural tariffs at the Trans-Pacific Partnership (TPP) talks this weekend.
Asia Pacific leaders are in Sydney for three days of ministerial negotiations led by the Australian Trade and Investment Minister Andrew Robb.
Mr Groser said the talks were entering a crucial stage, with issues such as agricultural market access and intellectual property yet to be tackled.
Federated Farmers' president Dr William Rolleston said Mr Groser appeared to soften his stance at the last round of talks and suggest he would consider an agreement which included some tariffs.
Dr Rolleston urged Mr Groser to settle for nothing less than eliminating those tariffs.
"We got some messages from our own Minister, Minister Groser that he would look at some outcomes that didn't involve the complete elimination of tariffs.
"We would ask him to stiffen his spine, and go back in there and bat for New Zealand."
Dr Rolleston said countries who refused to eliminate their tariffs should step aside from the negotiations and come back in at a later stage when those who are willing have completed their negotiations.
US President Barack Obama is aming to reach agreement between the 12 nations by the time they meet at APEC in Beijing in November.
However, bilateral talks between Japan and the United States stalled in Washington in September, with neither prepared to agree on reducing trade barriers for beef and pork.
Mr Groser said the three day meeting would try to get some progress, but he said agricultural market access and intellectual property were among those areas which still require substantial work to get closer to a conclusion.