Tim Groser is among trade ministers meeting in Brunei this week to try to clear the way for the completion of a Pacific wide trade deal by the end of the year.
Brunei marks the 19th round of talks for the Trans Pacific Partnership (TPP) before the APEC leaders meeting in October, where a deal is expected to be announced.
Trade ministers from 12 countries will discuss difficult areas like market access and intellectual property protection which must be dealt with to reach a deal.
Mr Groser says there's been a sea-change in the US to get a deal done quickly since Japan entered negotiations.
Radio New Zealand's economics correspondent says phasing out tariffs in politically sensitive areas like the dairy, sugar and textile sectors could be part of the price the US is willing to pay to do a deal.
Fonterra's market dominance and the drugs-buying agency Pharmac have been sticking points for the Americans.
Auckland University law professor Jane Kelsey says differences between the countries are too vast to be settled in just a few days and US pressure to accept a deal could lead to some countries walking away.