The New Zealand Nurses Organisation (NZNO) has petitioned Parliament to roll back its cuts to the new Dunedin Hospital.
They say what is proposed is a broken promise, that the government cares more about money than patients, and downgrading the hospital will lead to deaths.
About 50 mayors, councillors and supporters arrived to deliver the union's 34,406-signature petition to Parliament on Wednesday.
Dunedin delegate Linda Smillie set up the petition the last time cuts to the project were proposed - under the previous Labour government - but suspended it when that government reversed course.
"I couldn't stand silent when you see something that you know will affect your patients," she told RNZ.
She said it had gathered about 20,000 of the signatures at that point, but it had not been a struggle to get more people to sign on.
Nervous of public speaking, she made the trip to Wellington to deliver her petition - and in her speech at Parliament, she told the government to keep its promises.
"You have chosen to abandon the people of the South. We challenge you to keep your promise to us and build the southern tertiary hospital as agreed. Is it not more important to save lives, than to save money?"
NZNO president Anne Daniels said the new hospital must provide specialist tertiary-level health services, like surgery and cancer treatments.
That was partly because of the so-called 'golden hour', she said: patients should be at a trauma centre within an hour of being injured.
"Every minute that counts you lose brain cells, you lose heart cells, you lose muscle, and you put limbs in peril. Tertiary care will actually provide the care needed in any situation. If it is downgraded to a secondary-level hospital, that will not be able to be done."
She highlighted the huge section of the South Island the Dunedin Hospital is expected to cover for those tertiary services, noting that if it were not available people would have to go to Christchurch, putting further pressure on that metropolitan hospital.
A downgrade in Dunedin would also put the future of the Otago Medical School at risk, she said.
Speaking on the government's behalf, MP for Southland Joseph Mooney fronted up - railing against the heightened cost of the hospital.
Faced with frequent interruption from the petitioners, he spoke of how it would mean the hospital being one of the most expensive in the southern hemisphere - before one man stepped forward from the protest line to confront him about those claims.
Prime Minister Christopher Luxon took a similar line.
"As I've been saying consistently, I understand the frustration of the community about the hospital, it's been a total hospital pass from Labour to our new government, we're equally frustrated about it. But as I've been saying we're going to build a great hospital in Dunedin but it needs to be at $1.9b and within the budget.
"We can build a great hospital for that amount, but we're not going to build a hospital for $3b... the protests that were here today, they're going to catch up, the mayors I understand are going to catch up, with (Minister of Health) Shane Reti as well and talk about it further."
He said he had been to Dunedin twice and made his point very clear, but some work was ongoing.
"We've got a review process on looking at the new site, the old site, whether we scale back, what we scale back and how we actually run that process.
"What I'm saying is we are not building a hospital at $3b, which would be one of the most expensive in the southern hemisphere. But what we are doing and are deeply committed to is making sure they get a great hospital in Dunedin, but we're going to do it at the budget of $1.9b.
"At $3b that means we can't invest in Whangārei, in Tauranga, in Palmerston North, and also in Nelson Hospital. So we want to be able to make sure we can deliver infrastructure in New Zealand."
That kind of rhetoric was not good enough for the nurses union.
"Of course it's going to be expensive - the next hospital they build will be the most expensive hospital they ever built," Smillie said. "We promise, we promise, we promise, they've already promised, they've broken their promise. Their promises mean nothing."
Daniels said every day the government delayed final decisions on its exact plans for the hospital build would also add about $100,000 to the cost.
She also repeated the words of Labour's Ayesha Verrall, noting many of the costings for the Dunedin Hospital project had still not been made public. RNZ's official information requests for previously redacted hospital costings had also been rejected.
"They say safety's their priority? A lie," Daniels said.
Smillie agreed: "It is, it's bull***. it's not their priority - money's their priority."
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