John Key stated it as plainly as he dared in New York yesterday: failure to ratify the Trans-Pacific Partnership agreement would be a "massive lost opportunity" for the United States, he said, "because in the end is that vacuum isn't filled by the United States, it will be filled by somebody else".
He could have gone further and suggested the "somebody else" could be China. Talks involving China, India, Japan, South Korea, the Asean members and Australia and New Zealand are under way on a project called the Regional Comprehensive Economic Partnership.
It envisages, as the title suggests, much more than a trade agreement. An "economic partnership" is a code of practice for business of all kinds that crosses national boundaries and brings international living standards to countries that subscribe to fair rules of competition and secure property rights.
The TPP has written the world's first agreed charter of that scale. It has been agreed between 12 governments of the Asia Pacific and awaits ratification by their legislatures. If it fails to pass a vote in the US Congress, most of those 12 countries will transfer their energies to the RCEP.
Key had no need to spell out the implications to his New York audience, the Council for Foreign Relations, but his real targets are in Washington. Some of them - but not all - are seeking re-election for Senate and House seats. Some will be defeated at the elections on November 8, but all of them retain their seats until the next Congress is sworn in late in January. That "lame duck" period is a chance for legislators to do what is right, though it may not be popular.
Americans are well accustomed to their representatives doing this and they do not protest vehemently enough for the practice to become politically untenable. It almost seems to have tacit approval. The American public and the incoming Congress appear to accept that contentious things need to be done when the Constitution provides the opportunity.
Both presidential candidates say they want to renegotiate the TPP. Hillary Clinton will know, if Donald Trump does not, how long it took to get the TPP to the point of agreement and how hard it was. It would do the partners no harm to indicate to American voters that a renegotiation cannot be taken for granted.
Key dropped a slight hint in that direction yesterday, telling his audience, "When people say the deal can be modified and the parties can come back to the table, that relies on those 12 countries having the will to do that. There is a deal there. The deal is ready to be signed and in our view it is massively in the United States' interest to sign that deal."
Because, it bears repeating, if that vacuum is not filled by the United States, it will be filled by somebody else.
The TPP has not come from nothing. It grew out of the World Trade Organisation's stalled Doha round, which itself resulted from collapse of communism and almost universal realisation that competitive markets are the source of prosperity. If the US turns inward and protectionist under its next President, trading countries will look elsewhere for global progress.