Prime Minister Jacinda Ardern says there is a fifty-fifty chance of a deal being reached on the Trans-Pacific Partnership (TPP).
Ms Ardern is on her way to Vietnam for the APEC forum where the 11 TPP nations will meet on the sidelines to finalise the controversial trade pact.
Speaking on the plane, she said she wanted concessions to allow New Zealand to dump the rules allowing foreign corporates to sue governments in overseas tribunals, though conceded it would be hard to convince the other nations.
"There are 10 other countries at the table - whether the agreement is concluded will come down to a number of issues, not all of which involve New Zealand," Ms Ardern said.
Former trade negotiator Charles Finny said the government should sign up even if they did not get what they wanted.
He said the Investor State Dispute Solution regime faced huge opposition worldwide, and policymakers were already considering taking a different approach to ensure foreign investors got the same protection as domestic investors.