Everything points to new Prime Minister Jacinda Ardern emerging from a TPP leaders' summit in Vietnam tomorrow night with a deal finally done.

If the leaders can't do it tomorrow, they will never do it.

It is a make-or-break meeting for the Trans Pacific Partnership trade deal which was begun in 2008 by Labour Trade Minister Phil Goff and concluded in 2015.

Chief negotiators and trade ministers have been meeting in Vietnam this week thrashing out the last points of contention for a green light by leaders.

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The TPP leaders' meeting at Apec is an artificial deadline but it was set early in the year after the US withdrew from TPP.

Japan has assumed leadership of the group since January when Donald Trump pulled the US out and threw in the TPP captain's badge.

Shinzo Abe picked it up. As the leader of the largest remaining economy in the TPP and recently returned in an election with a huge majority, he is at the height of his political powers of persuasion.

TPP has become an emblem for his own drive to liberalise the heavily protected Japanese economy into the 21st century. It also enhances his own standing as a regional leader.

For some time Abe's message has been to the remaining countries, if you can't commit, sit it out until you can commit and let those who want to get on with it get on with it. If one or two want to sit it out, so be it.

New Zealand is one of those that want to get on with it - despite the new Labour-led Government trying to get out of the Investor State Dispute Settlement provisions through side letters country by country.

It is not likely to have much success with that, because other countries have also made the hard-sell domestically to accept ISDS in TPP and it would be difficult to justify an exception for New Zealand.

Failure to get many acceptances for the side-letter is not grounds for Labour to withdraw from TPP or to sit it out for a while. The party is not going to die in a ditch over it.

Labour has had concerns about ISDS which sets up an arbitration system to deal with investor grievances against grossly unfair treatment by governments.

But ISDS was never one of Labour's five bottom lines. It wanted to make it impossible for corporations to sue the Government for regulating in the public interest. But that was met by the many exceptions to when ISDS can be applied.

That concern was met, along with its concerns on Pharmac, Treaty of Waitangi, tariff reductions, and most recently farm and house sales to foreign-based investors by law changes proposed by Labour itself.

Failure to join TPP presents more problems for Labour than staying out - for example, the existing disadvantage New Zealand beef exporters to Japan against Australian exporters would be increased.