A Trans Pacific Partnership deal could be announced as soon as today if negotiators clear the final hurdles, including the biggest remaining one involving dairy import limits.
Prime Minister John Key left New York yesterday but Trade Minister Tim Groser remains in Atlanta at the talks, which were pushed back a day - a sign the agreement is verging on a breakthrough.
"I'm pretty optimistic it will come together [this weekend] - 80-20," said Alan Wolff, a former US negotiator who now leads the American National Foreign Trade Council, a commercial association.
Trade ministers from 12 countries are negotiating the controversial pact, which would cut trade barriers and set common standards for 40 per cent of the world's economy and be the biggest free-trade deal in a generation.