The Maori Party is threatening to split with National over plans to remove reference to the Treaty of Waitangi when state-owned assets are sold.
Maori Party co-leader Tariana Turia said if it came down to the wire the Maori Party would have to "consider its position" with the Government.
National is beginning to consult Maori on its plans to sell up to 49 per cent of four state-owned energy companies and further reduce its shareholding of Air New Zealand.
The Government is being accused of selling Treaty rights to the highest bidder following suggestions Treaty protections will not be included in new legislation to enact the partial sale of state-owned assets.
It is required to pass legislation to remove the four energy companies from the State-Owned Enterprises Act to proceed with the sales.
Turia says National did not discuss the removal of the Treaty clause with the Maori Party during confidence and supply negotiations and they were not happy with it.
The party would talk to iwi and constituents and take advice from them.
If they told the party to leave its arrangement with National they were prepared to do so and would not stay in the arrangement "at all costs".
"If they remove Section 9 there will be no reason for them to consult with Maori about issues so they would actually be denying that the Treaty exists."
The Party had to be very clear about who they represented, Turia said.
"It's really in the iwi hands, the iwi have to stand firmly on this issue because we're here representing their interests and our peoples interests."
The issue would cause tension at Waitangi Day commemorations over the weekend and at least one iwi leader had suggested Maori hold a hikoi in protest of the move, she said.
State-Owned Enterprises Minister Tony Ryall said Section 9 of the SOE Act - which requires the Crown to act in a manner consistent with the principles of the Treaty - was left out of legislation enabling the sale of Contact Energy in 1999, as well as the sale of other state-owned assets in the late 1980s and early 1990s.
"We're interested in seeking Maori views on this."
Co-leader Pita Sharples said the party was not in government to ignore the real issues.
"This Treaty clause is about New Zealand. It's not just about Maori. The Treaty is all of our Treaty and this clause protects us and our natural resources, us New Zealand, and that's really really important to me."
National has said it will keep Section 27 of the SOE bill.
But Sharples said that was not enough because it meant the Treaty only had to be considered in regards to designated aspects.
"It only deals with parts of things and that's not what we want. We want the clause that apply to the whole deal."
He said the Government obviously envisaged future issues with areas such as water rights.
Maori did not want assets sales at all, he said.
Labour leader David Shearer said the tension between the Maori Party and National raised concerns about the stability of the Government.
"The Prime Minister John Key electioneered on the fact this was going to be a stable Government and within one month effectively of this Government coming into operation its already seen to be unstable."
If the Maori Party did walk away National would be left relying on one ACT MP to hold the Government together, he said.
Shearer said the Maori Party would likely be upset at not being told about the Treaty clause but it did not concern Labour, who was opposed to asset sales in any form.
"One would have expected that they told the Maori Party, before they went into this agreement, what exactly was coming down the track in terms of the sale of the assets."
He said Labour was also concerned about the likelihood that the social responsibility clause would not apply under the new legislation.
Removing the Treaty and social responsibility clauses from new legislation opened the way for foreign ownership and eventually the total sale of the assets, Shearer said.
"It's quite clear that what they're doing is putting profits before people and enabling overseas buyers more access to our assets."
The Mana Party said National was essentially going to throw the Treaty out by removing the clause.
Deputy leader Annette Sykes said the Maori Party should terminate its relationship with National over the issue.
"They need to be genuine with their challenge. Walk away Maori Party. End the relationship and make a principled stand."
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