Prime Minister John Key has used a speech to the Council on Foreign Relations in New York to talk up the importance to the United States of the Trans-Pacific Partnership free trade agreement.
"The region will not wait for you," he told the independent, non-partisan organisation on Tuesday.
"Asian countries are determined to grow and they realise that to grow they need to remove trade barriers - this will happen with or without the United States."
Mr Key said the TPP would maintain US leadership and influence in the region, and every effort should be made to get it over the line.
He said that while some in the US "might not think it is the perfect deal" the idea that it could be renegotiated was unrealistic.
Both presidential candidates, Hillary Clinton and Donald Trump, have said they oppose the TPP.
But US President Barack Obama is a strong supporter and hopes it can be ratified by the US Congress during the so-called lame duck period between the presidential election on November 8 and the inauguration of the new president on January 20.
President Obama's position is that the US must ratify it or China will set the global trade agenda.
The 12-nation agreement, covering 40 per cent of global trade and 800 million people, was signed off in October last year.
To take effect it must be ratified by at least six countries that account for 85 per cent of the group's economic output, which makes the US essential.
The partner countries are New Zealand, Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, Peru, Singapore, the United States and Vietnam.