Key says no area off limits in trade talks and partners comfortable with NZ's agriculture stance.
The end of 2013 has been set as an informal deadline by which to conclude the Trans Pacific Partnership, in a meeting in Cambodia chaired by American President Barack Obama.
But Prime Minister John Key said the TPP leaders also recognised they might have to have a full summit "to shove it over the line".
The United States President and Mr Key met leaders from five other countries at the East Asia Summit in Phnom Penh that are parties to the TPP talks: Singapore, Brunei, Australia, Vietnam, and Malaysia.
Mr Key said Mr Obama was "totally committed" and the leaders would try to get a deal next year.
"That's the ambition if we want to see this deal completed."
They also agreed the deal should be comprehensive, as agreed at Mr Obama's Honolulu Apec summit in 2011 - meaning no area is off limits and that all tariffs on all goods and services would need to be eliminated.
The really hard negotiations over agriculture and intellectual property were put on hold until after the US presidential elections.
Mr Key reiterated New Zealand's position that if it did not include agriculture, Kiwis wouldn't be part of it. But he said all the other leaders were comfortable with that.
There would be a long phase-in for some countries. It would take some time to eliminate tariffs on agriculture, he said. "This thing isn't going to happen overnight, in day one.
"But that is the normal structure for an FTA and everyone is comfortable with that."
The hard bargaining starts from here, the next and 15th round due to be held in Auckland next month.
Mr Key said he was more optimistic since the meeting about the deal. "Just looking at the President this morning and his determination, I am much more confident than when I walked into that meeting."
Asked if a trade ministers' or leaders' meeting would be held, he said: "We have confidence in our negotiating teams and confidence that they can pull together a deal that can be concluded. But there is a recognition that in the end these deals are always political and it may require the intervention of leaders." Sometimes "it takes one final shove to get these things over the line".
Four other TPP countries were not there because they are not members of the East Asia Summit: Chile, Peru, Mexico and Canada.
Meanwhile, Mr Key was reported to have had an informal discussion yesterday with Mr Obama about the case of Kim Dotcom but refused to confirm if he had.
Asked if the case came up when he spoke to the President at the summit leaders' dinner on Monday, he said "No, not last night." Asked if it had come up since, he said: "Well, I'm just not prepared to go into those details." Dotcom is fighting a US extradition order on charges of internet piracy.