The Minister for Trade Negotiations thinks there is a 70 percent chance of getting a basic deal on the Trans Pacific Partnership done within a few months.
The agreement is a step closer after a Congressional committee agreed on fast-track legislation.
This still needed to go to a full Congressional vote but Tim Groser was cautiously optimistic.
Mr Groser said two negotiating powers were very conservative, Japan and Canada, and there were difficulties still standing in the way.
Fast-track legislation gives a US president the power to make trade deals that cannot be amended by Congress, which can only accept or reject the agreement.