An expected announcement the 12-country deal had been agreed was twice pushed back yesterday, before being rescheduled for early today, amid speculation dairy market access and pharmaceutical patent lengths were two final sticking points.
''I actually think that may be a good sign. I think that New Zealand is really pushing hard for a better deal on dairy, to try to get much greater market access.
''There's a lot at stake here.''
Prof Patman was reasonably optimistic an agreement could be reached, but if this round of talks failed, it would be more difficult to reach the December deadline.
That is seen as a crucial date because next year the United States will be consumed by the election for president.
If not agreed this year, it would go on the backburner until the year after next.
This month's Canadian election was another complicating factor.
''It's all a bit iffy, really.''
While a supporter of the deal, and of free trade, Prof Patman acknowledged the role of staunch critics, most notably Prof Jane Kelsey, whose lobbying probably meant that any deal reached would be better for New Zealand.
However, he had little time for people whose concerns led to outright opposition to multi-country trade deals.
''There's a lot of countries who still pretend that they have sovereign control over their economy; they still operate on the basis that they can determine their own destiny.
''We in New Zealand haven't been labouring under that assumption for some time.''
New Zealand's reliance on exports meant it had to be part of such a large trading bloc.
Parts of the deal were likely to be ''disagreeable'', he said.
In New Zealand's favour, the Americans would soon be exporting more dairy than New Zealand, which meant it also had a vested interest in gaining more access to markets for its own product.
The secrecy and lack of reliable information meant relying on leaks and the occasional statement from negotiators, including the ''self-interested slant'' from the respective players.
It meant speculating on the deal's outcome was difficult, he said.
