Nurses will vote today on the latest pay offer from their district health board employers.
Online voting closes at 5pm on the DHB's revised offer, an offer that has controversially in the view of some nurses been backed by the Nurses Organisation.
The outcome of the ballot is far from clear but widely expected to be close. If a simple majority rejects the pay offer, which is a complicated one, a planned 24-hour strike on Thursday will proceed.
Nurses have not gone on strike for 30 years and never under current Life Preserving Services (LPS) agreements designed to ensure patients are safe and well cared for during a strike.
It's a high-stakes time for the union which also has come under fire on social media with intense debate and criticism of it by some nurses for failing, in their view, to advocate strongly enough for nurses against their employers over years.
A casual registered nurse and union member, Danni Wilkinson, a month ago left the so-called Nurse Florence Facebook group, which she was helping to administer, to launch her own breakaway group.
Ms Wilkinson told RNZ her union membership lapsed in early May but she rejoined on 18 June.
She said the direction she wanted to take online discussion differed from that of the anonymous Florence, so she decided to launch her breakaway group, New Zealand Nightingale Fight For Fair Pay.
Ms Wilkinson won't say where she works casually as a nurse, to avoid "bringing our employment situation in DHBs into disrepute".
She said the "Florence" group did good things, but she wanted to do different things online.
"I had some ideas that I wanted to implement and get moving and trying to work with Florence to get those ideas happening was proving quite difficult.
"She wanted to maintain the initial integrity of the page and keep it about stories. I wanted to start sharing some facts and information and just get things moving a bit more and we had a difference of opinion on that".
Ms Wilkinson said nurses had become apathetic but social media had changed that: "I think it's been vital insofar as this particular campaign ... because our union had traditionally [been] quiet and not particularly active, or hasn't been active for quite some time, the social media side of things has given I guess the union a kick up the bum and they've had to step up and be a bit more active."
She added there may be a need for "fresh blood" in the union in future, but that would be a question for after the current pay negotiations.
The Nurses Organisation rejected those accusations, saying emotions were high for members and it had been a long negotiation, but it had worked very hard and well for its members.
That may be an argument for another day. Right now, DHBs and the union are in the midst of legally required contingency planning for a strike on Thursday, should that be the result of the ballot.
The union today provide DHBs with a list of the life preserving services responders who will work on wards during the strike.
The union's associate professional services manager, Hilary Graham-Smith, said at the weekend she was optimistic they would get enough nurses to fill the vital roles.
"I think once we got our message out to nurses that being a life preserving services responder is strike enabling, so they're enabling their colleagues to go on strike, and once members have understood that, I think it's been easier for them to make the decision about whether or not to be an LPS responder."
If nurses vote to veto the pay deal and prepare to strike on Thursday, it will be unprecedented.
DHBs aren't commenting on this. However, their national contingency planner, Anne Aitcheson, said nurses were the largest workforce group in hospitals.
"It's a very large number of staff. It makes the situation very complex for those who will be working with less people available, and the nurses are the front-line workers for most departments and services in the hospitals, and in our community."