National Party leader Christopher Luxon has, eventually, ruled out a referendum on co-governance.
But his potential future coalition partner David Seymour said Luxon must face up to tough issues and not run away.
Seymour has demanded a referendum on the issue.
Co-governance very broadly describes arrangements for governments to share decision-making with iwi or other groups.
The Government has been considering steps in developing a plan to realise United Nations obligations around Māori self-determination.
Luxon today said there was no consensus on what co-governance actually meant in the local context.
"The country's pretty confused as to what we're actually talking about. At the moment it's very unclear.
"I have concerns about co-governance as it moves from management of local and natural resources into the delivery of public services."
But he then said the Government had to make a case about what it was doing with co-governance.
After repeated questions on the issue, he said calls for a referendum now were unhelpful.
"I appreciate he's got a view about what he might want to do in his party," Luxon said of Seymour.
The National leader eventually ruled out a referendum on the issue, saying he saw no need for it.
Luxon said he wanted a genuine, high-quality conversation about the issue.
Seymour today urged Luxon to keep an open mind.
"The truth is, you don't get to rule things out before the people vote. Actually, this is a necessary but difficult conversation."
Seymour added: "He just needs to keep an open mind about how he can make New Zealand a better place, and not run away at the first sign of controversy."
He added: "The problems won't go away by ignoring them."
Māori Development Minister Willie Jackson took a paper to Cabinet with feedback from Māori on the United Nations Declaration on the Rights of Indigenous Peoples.
Co-governance has long been used in Treaty settlements, including over specific areas of land or natural resources.
The He Puapua document was produced in 2019 to advise how New Zealand could realise its commitments under the UN declaration.
The document included a roadmap to 2040 imagining various co-governance and Māori-run arrangements to address inequality.
Seymour yesterday said Prime Minister Jacinda Ardern must clarify the Government's intentions around co-governance.
"Act has proposed a referendum on co-governance, that the Government pass legislation defining the principles of the Treaty, in particular their effect on democratic institutions."
He added: "If Jacinda wants to continue down the path of co-governance, she needs to make her case and it needs to be stronger than just that the powerful Labour Māori caucus want it."
Seymour said a referendum would allow for meaningful debate.
"No society in history has succeeded by having different political rights based on birth. Many New Zealanders came here to escape class and caste and apartheid."
Expectations tempered around return to surplus in 2027/28.