Government says it is winning the argument and has public on side.
Prime Minister John Key went on the front foot yesterday over the Trans-Pacific Partnership, releasing an official report two weeks early in a bid to head off a renewed campaign against it before the signing ceremony in Auckland next week and a tour of New Zealand by a leading United States critic.
He claimed that the deal was "25 years in the making", despite the TPP having taken five years to negotiate.
However Mr Key was referencing New Zealand's longstanding bid to get a free-trade deal with the United States, the biggest economy in the world, which is effectively delivered by the TPP.
Mr Key said the Government had the public on its side and that TPP opponents had made up their minds about it before they saw the text or the national interest analysis.
"I think we are winning the argument actually with the New Zealand public who have seen for a long period of time that asking New Zealand businesses to compete with one hand tied behind their back in the biggest economy in the world, the United States, and the third largest like Japan, puts us in a disadvantaged position," he said at his post-Cabinet press conference.
"This is a free-trade deal that gives us access to 800 million middle-income consumers. Its economic benefits are about two-and-a-half times the size of the China FTA.
"Successive governments have been trying to conclude this deal and actually, it's great for New Zealand."
Earlier, Trade Minister Todd McClay released the national interest analysis of the TPP, a 279-page document which largely sets out the benefits of the deal for New Zealand.
It did concede that the large number of countries in the TPP, 12 altogether, and the number of investors meant a higher risk of attracting a case under the investor-state dispute settlement (ISDS) rules. None have been lodged under any other New Zealand FTA.
But Mr Key said there was no expectation New Zealand would be sued. The ISDS rules were there to protect New Zealand businesses abroad.
"Those provisions are there but those provisions are very much about protecting New Zealand investors in off-shore markets where they might have less confidence about actions of the government."
He accused Labour leader Andrew Little of not being able to answer the most basic question he got asked, namely whether he would support it or not.
"He was floundering around on Radio New Zealand this morning like it was the first time anyone had ever asked it," Mr Key said.
Labour supports the reduction of tariffs but opposes the TPP, claiming that it undermines New Zealand's sovereignty in not allowing a future Government to ban house sales to foreigners - which Labour leader Andrew Little says he would ignore.
Mr Key said that would be a "breach of good faith".
Parliament will not get to vote on the TPP but will consider enabling legislation. Labour has not decided how it will vote on individual bills before seeing them.
United States TPP critic Lori Wallach is beginning a tour of New Zealand with co-critic Professor Jane Kelsey and spoke at the Auckland Town Hall last night.
Trade ministers of the TPP countries are due to sign the agreement next Thursday although each country has to then go through its own ratification process.