A failure to strike a deal on the Trans-Pacific Partnership Agreement this weekend could see it delayed by up to two years.
Negotiators are continuing to finalise details of the controversial trade deal, also known as the TPPA or TPP, and it could be signed as early as tomorrow. If it's not, Victoria University associate professor of law and TPPA expert Meredith Lewis says it would be a huge blow to US President Barack Obama.
"President Obama has made it a centrepiece of his trade agenda to get the TPP passed," she said on the Paul Henry programme this morning.
"We're at the endgame, and it's very crucial that a deal be reached this week in order for the deal to be passed by the US Congress this year. There's a lot of pressure on the negotiators to get things done."
The US presidential election is more than 15 months away, but the drawn-out campaign and uncertainty around who will be take the helm of the world's biggest economy means further progress on an unsigned TPPA would be unlikely.
"If it spills on, if it doesn't get concluded this week, it really can't get through the US Congress before the next election cycle starts, and we're talking about probably a two-year delay – and everyone wants to avoid that," says Prof Lewis.
Even if the TPPA is signed this weekend, that doesn't necessarily mean it's on. It will still need to be approved by Congress, but Prof Lewis says as representatives have already given Obama fast-track authority to negotiate the deal, it's unlikely they would then reject it.
New Zealand is pushing for greater access to overseas dairy markets, but Prime Minister John Key is playing down expectations tariffs will completely eliminated, particularly in heavily protected markets like the United States.
"I remain of the view that we will get a deal that's a good deal for dairy," he says.
"It may not be 100 percent elimination of tariffs, but I think there's a lot of progress that can be made and a lot of the market's going to be opened up – partly because it's in the United States' best interests to have a good deal."
Prof Lewis says it's likely New Zealand's negotiators have significantly "recalibrated" their expectations as the discussions have gone on. She believes New Zealand would likely sign the deal even if there was nothing in it for the local dairy and farming sectors.
"The negotiators are going to try as hard as they can to avoid that situation, but at the end of the day, it would be so difficult for New Zealand to walk away from this deal, even if it's not what it hoped," she says.
"From a political perspective, it seems like such a blatant expression of failure if you walk away; you're saying 'our negotiators weren't able to make any headway against the other countries'. It seems so weak, and so my guess is even if the deal isn't optimal, it's better politically to sign it and put a positive gloss on it, to the extent you can."
National MP Judith Collins, appearing on the Paul Henry programme alongside Labour deputy leader Annette King this morning, said we are currently paying "huge tariffs" to get New Zealand beef and lamb into the US.
But even if the deal isn't perfect, she thinks it's better to be "in the tent" than stuck outside, missing out.
"Every single deal that we've done on free trade, whether it's Labour or National, we have always got significantly more in the end than what was ever envisaged."
Labour has serious concerns about the TPPA, particularly what it means for drug-buying agency Pharmac and the secrecy surrounding the talks. The only glimpses the public has had of the TPPA have come from unauthorised leaks, often months out of date.
"We're in favour of free trade, and of course we've signed deals, so it's not that we're opposed to them," says Ms King. "I think the real problem with this is we keep being told little snippets of what might be in it, but nobody really knows."
Prime Minister John Key says Labour's scepticism of the TPPA is "really disappointing".
"It was [former Labour Prime Minister] Helen Clark that started the negotiations for TPP, it's been the Labour Party that alongside National has seen the great benefits for New Zealand from free trade. But there's a lot more work for us to do over the course of the next few days."
Former MP Hone Harawira is the latest high-profile voice to speak out against the deal, saying it will take priority over the Treaty of Waitangi and leave Maori worse off.
The Mana leader wants President Barack Obama to visit him and renegotiate the deal over some fishing and beers.