The Cancer Society and a number of NGOs have penned an open letter urging National and Act leaders to rethink their stance on scrapping the Māori Health Authority.
Christopher Luxon and David Seymour have said they do not support a Maori Health Authority and will get rid of it if they win next year's election.
The open letter says they stand in solidarity with Māori leadership and are united behind the establishment of the Māori Health Authority.
The letter goes on to say its establishment is central to Te Tiriti o Waitangi and will help ensure everyone has the same access to good health outcomes.
Signatories include the Lung Foundation, Hāpai te Hauora, Kidney Health NZ, Stroke Foundation NZ, Breast Cancer Aotearora Coalition, Gynaelogical Health Foundation, Hei Āhuru Mōwai, Support Crew Hei Whare Awhina - and the list is growing.
Cancer Society Medical Director Dr George Laking said they had garnered support from a broad range of organisations in the last 24 hours.
He said a majority of them were non-Māori organisations, which he said was telling as there was overwhelming support for the establishment of the authority.
"These are a group of non-govermental organisations of those working in health, who have an understanding of how our health system works, with some independence from the government, in contrast to those who work in the health system who may not be able to speak out - whereas we can."
In response to the letter, the Act Leader David Seymour said it was a shame to see an organisation with such an important cause being hijacked by political activism.
"They should stick to advocating for all cancer patients instead of stunts like writing open letters to politicians.
"If the Cancer Society wanted a dialogue with me they could have got in touch and explained why. Putting out an open letter like this is just a stunt."
Laking said the authority was simply a way of solving a problem that everyone knew existed.
"It is quite a straight forward way of doing it - which is bringing the experts to remedy the problem that we have, it is logical to put the commissioning power into the hands that understand it the best," Laking said.
"If they [Act] want to use plane analogies, well it is desirable to entrust the flying of the plane to the pilots who understand what is at stake with the business," he said.
The National Party recognised the health inequities Māori faced and described them as shocking.
It stood by its stance on promising to dissolve the authority if it won the next election, saying it was a token organisation.
"We should be focused on actions that will improve outcomes for Māori, not on token new organisations and more layers of bureaucracy that the government admits won't make a difference for five years.
"National believes we don't need two separate systems to deliver public services. We need a single system that has enough innovation and components in it that can deliver better outcomes for people on the basis of need."
Health Minister Andrew Little said the open letter showed that people across the health sector who knew the system wanted to see the authority implemented.
"The big challenge is to make sure that we get access to primary health care for Māori way better than we are doing at the moment, that is the preventative.
"The idea that it is more bureaucracy, I totally reject that. The idea that it is separatist, it is not. There is one health system but we need Māori leadership for improved Māori health services for Māori and that is what we are doing," Little said.