The Maori Party attempted to distance itself from National's tax-cuts package yesterday on the grounds it does little for the low-paid, but said it voted for it to honour its confidence and supply agreement.
Meanwhile, already soured relations with Labour over the bill intensified.
Maori Party Waiariki MP Te Ururoa Flavell said that for the record the party was not consulted on the bill before its negotiations with National.
"This is very much an initiative of the National Party ... and they will own it as such."
The tax cuts to be phased in over three years will begin on April 1 next year, though income-earners earning under $45,000 will get a tax cut only if they have no children.
No taxpayer will pay more tax than at present but some will pay more at the end of the three years than they would have if Labour's tax regime had remained.
Mr Flavell said it was difficult to accept that those earning under $40,000 would receive no tax cut in the first year. "No member of Parliament should be comfortable that low-income families continue to struggle."
He said families were struggling to buy food and pay for power, and forced to abandon their homes which were becoming increasingly more vulnerable to mortgagee sales.
The bill did little to address those issues and he was disappointed it did not cut tax for the majority of voters in his electorate.
"But day three in this 49th Parliament is not the time that the Maori Party will wave the white flag of defeat, to run away from the opportunity to make a difference."
Labour continued to accuse the party of "betrayal" for supporting the package.
But Te Tai Tokerau MP Hone Harawira launched a stinging retaliation, saying Labour was "poncing about in pious and sanctimonious rage about mana-enhancement and the perceived failings of the Maori Party".
He said the Maori Party - formed over the foreshore and seabed law - had been "born out of the betrayal of 50 years of blind loyalty to a regime which took the Maori vote and spat on the Maori hand that offered it willingly".
"The Maori Party will remain forever a party in this House and a player in the governance of this country, thanks to the treachery, the duplicity and the seditious betrayal of the Maori people."