Māori Party co-leader Te Ururoa Flavell is defending his Māori land reform bill after Mana leader Hone Harawira labelled it "poisonous and destructive".
Mr Harawira, a Māori Party ally, is not the only opponent of the Te Ture Whenua Māori Bill, which proposes major changes to the governance and administration of the 27,000 titles of Māori land.
Labour says the legislation is a fundamental shift in principle and New Zealand First has accused the Māori Party of elitism.
New Zealand First leader Winston Peters said future costs of the bill would disadvantage Māori landowners.
"[The Māori Party] have been fiddling around with this legislation ... and yet the Māori Land Court would not be supportive of it. Those who are experienced in the Māori Land Court would not be supportive.
"So exactly who are the drivers here?"
Telling landowners they could always go to the High Court showed a lack of understanding of the economic position of Māori, he said.
"They're elitist and they're pressing an economic prescription that is highly dangerous to Māori. They are highly supportive of mass immigration to this country, which is destructive to Māori."
Labour's Ikaroa Rawhiti MP, Meka Whaitiri, said there was one glaring difference between the current legislation and the new bill.
"The Act talks about protecting land, the bill talks about utilisation," she said.
"We have a fundamental principle shift."
In particular, the plan to move the dispute resolution process from the Māori Land Court to a newly created new Māori Land Service is raising concerns.
But Mr Flavell is sticking by the legislation.
"The land is a taonga. It should not be able to be alienated at all," he said.
He believed the introduction of tikanga Māori in the bill would help prevent cases from getting to court.
If whānau or iwi could not sort out their disputes through tikanga, there would be a facilitator, possibly outsourced by the court, to handle the issue. After that, the Māori Land Court would determine the avenue, and it would be up to those involved in the dispute to determine who paid for that.
But Ms Whaitiri said there was not enough detail.
"I don't think the Māori landowners should trust the minister until he is able to actually say 'this is what the Māori Land Service is, this is where it's going to be, this is how it's going to benefit Māori landowners'.
"Is it a free service? Is it a paid service? who's going to deliver it? Is it going to be Land Information New Zealand - a Pākehā organisation who doesn't understand the intricacies of Māori land tenure? The point is, no one can answer those questions."
Mr Flavell said he was hoping for about 12 regional offices.
He said the government had consulted widely, having held 150 hui and made 129 amendments while removing 28 clauses from the bill.