Maori Party co-leader Tariana Turia says Labour leader Phil Goff was being "bloody patronising" when he warned her party to be wary about making an agreement with National.
Mr Goff said the Maori Party should act with caution. Although it was entitled to make a deal with National, it would face an electoral backlash because most of its supporters gave their party vote to Labour.
Mrs Turia labelled Mr Goff's comments "bloody patronising behaviour" and said he was scaremongering to try to derail the agreement process.
"He's trying, once more, to frighten our people into saying we should sit with Labour," she said.
"Well, Labour didn't even invite us to sit with them in the last government and our people are sick and tired of being told what to do. He should stick with rebuilding the Labour Party instead of trying to dismantle others."
Support for a deal - which would make the National-led government more secure over the next three years - is reported to be strong in the nationwide hui the Maori Party is holding to gauge opinions of its draft agreement.
It is expected to be the first deal the National Party signs, although others with the Act Party and United Future leader Peter Dunne are expected on Monday.
It is expected to give the Maori Party two ministerial posts outside the Cabinet in return for support on confidence and supply.
Mrs Turia said the hui had shown a strong feeling that "red or blue", it was critical to have a Maori voice in government.#She believed she had the confidence of the Maori people over the issue, and Mr Goff should have more faith in them to do what they believed was right.
A spokesman for Prime Minister-elect John Key said: "We are looking at forming a government and we don't really care what Phil Goff has to say. It's patronising, isn't it?"
Mr Goff said National's record included 25 per cent Maori unemployment in the 1990s, and the Maori Party was taking "a real risk" by supporting it without fully knowing how its policies would affect Maori families.
He also criticised the Maori Party for limiting its hui to its own party members, saying the majority of Maori were Labour supporters.
Mrs Turia retaliated by attacking Labour's record. "People know Labour took the seabed and foreshore away from them. They also know that while Labour goes and loudly tells our people everything they do for them, the most empowering opportunities have come from National governments."
She said kohanga reo, kura kaupapa and progress in health and social services all came from National.
Mrs Turia has undertaken to report back to Maori every three months on how the governing arrangement is going, indicating she is proceeding with caution.
Yesterday, Dr Sharples said at a hui that the issues of the seabed and foreshore and the future of the Maori seats in Parliament would be reviewed as part of a wider constitutional discussion.#The Maori Party-National agreement is expected to be signed on Sunday afternoon.
National's agreements with United Future and Act are also expected to include ministerial positions outside the Cabinet and policy concessions.