And I've got highly confidential but very clear political guidelines from the Prime Minister about what I should be doing.
He had a team of about 15 with him "working their proverbials off" around the clock and some of the key stakeholders such as the chairman of Fonterra, John Wilson and the chairman of Dairy Companies of New Zealand. He said it was an achievement to get dairy on the list of the final three issues that had to be dealt with because it was not there at the Maui ministerial meeting at the end of July.
"I felt under as intense pressure as I have ever felt in the last 30 years as a New Zealand negotiator because I felt completely and totally isolated," he said. "Now everyone understands that New Zealand is not going to be pushed out of this negotiation and the issues that would push New Zealand out of this negotiation, which is dairy ... this has got be solved in a way that New Zealand can live with."
He said the negotiations were going around the clock and he was just about to try and get a couple of hours' sleep until he was called for another session.
He said it was clear there was a "massive push" to do the deal.
"It's got the smell of a situation we occasionally see which is that on the hardest core issues, there are some ugly compromises out there.
"And when we say ugly, we mean ugly from each perspective - it doesn't mean 'I've got to swallow a dead rat and you're swallowing foie gras.' It means both of us are swallowing dead rats on three or four issues to get this deal across the line."
The outstanding issues are dairy, autos, and IP on pharmaceuticals, especially biologics - medicines made from organisms.
On the issue of Helen Clark's comments about the TPP - she said it was unthinkable New Zealand wouldn't be part of the deal - he said she had added a crucial rider - "provided the deal was good".
And that was the same position the Government had.
"I think it has been extremely helpful in terms of uniting New Zealand that our former Prime Minister has said what she said."
Mr Groser said he did not take Labour or its leadership for granted on TPP.
"They haven't got a position on TPP and I fully respect that and if I were in their shoes, I wouldn't have a position either because I would say 'I don't know what the deal is.' That is a perfectly rational position to take."
But as a point of general principle, what Helen Clark had said was the essential truth: "Provided we can deliver what makes sense from an overall New Zealand Inc perspective, it would be a nightmare for New Zealand to be excluded from it."
If the deal is not done tomorrow, there will be one last chance, at Apec in the Philippines in November.