In September the United States agreed to join New Zealand, Singapore, Chile and Brunei in the "Comprehensive Trans-Pacific Strategic Economic Partnership Agreement". Now Australia and Peru have been added. The group has been dubbed the P7.
Negotiations would be more complex but produce better results, Mr Groser said on TV One political show Agenda today.
"It's a more realistic way to proceed with the United States. If we'd just gone head to head with the US when the only real hard trade issue is dairy I don't think that, given the imbalance of relative negotiating power, we would have got what I think we're capable of getting in this more complex negotiation."
He was confident of a "bigger strategic result".
Other countries with good prospects for deals included India, Korea and Japan.
"In the 30 years I've been involved in this issue I have never seen a more promising situation," he said.
Mr Groser was keen for New Zealand to make headway with the European Union but did not think negotiations would happen until the Doha Round ended.
Mr Groser was optimistic that it could be concluded successfully and said any deal would benefit New Zealand because it had the most to gain from removing export subsidies.
