Labour leader Helen Clark has come out in support of entrenching the Maori seats as parties jostle for Maori Party support before Saturday's general election.
Last week Miss Clark said she did not have a problem with the step and yesterday her language was more positive.
Today she stepped it up even further saying it was the only fair thing to do.
"I think we now need to move forward on entrenchment," she told Sunrise on TV3.
Entrenching the seats, which means a 75 percent majority vote in Parliament would be needed to abolish them, is a bottom line for the Maori Party in any post-election negotiations.
National leader John Key yesterday said entrenchment would be a matter for post-election talks. His party's policy was to eventually scrap them.
If National changes its position and Labour supports the move the entrenchment is likely to go through.
Labour's move puts the pressure on National in coalition talks but at the same time it makes the Maori Party more likely to support National - that would be the only way of getting that party to agree to entrenchment.
The Maori electoral option gives Maori voters the option every five years to enrol on the general or Maori roll.
The number of voters on the Maori roll determines how many seats there are.
Miss Clark said right-wing parties were determined to scrap the seats.
"I think the issue of entrenchment is the fair thing to do. Its entrenching the option, its entrenching the definition of Maori electoral population and its entrenching the formula whereby the seats are allocated," she said on TV3.
Miss Clark said Labour and other left wing parties had supported entrenchment in 2001 when a review of MMP was done but there was strong opposition.
"But I think the time has come."
Asked why she was willing to support entrenchment now, but not in 2005 when National leader Don Brash was determined to scrap the seats, Miss Clark did not directly answer.
She instead used the question to say there was little difference between Dr Brash and Mr Key except in how they presented their message.
"A smile doesn't take away this is a very right wing party that's trying to get into Parliament."
United Future and ACT have both locked in support for a National led Government.
Labour have the Greens and Progressive MP Jim Anderton.
Depending on whether NZ First returns to parliament and what share of the party vote both the big parties get, the Maori Party could be crucial.
Mr Key yesterday said the Maori Party could support either Labour or National and he would be happy to work with it.
"I have made it clear to the Maori Party in the discussions that we've had that abolition of the Maori seats is not a bottom line.
"They have never ever raised with me the issue of entrenchment now you know I'm not ruling it out, but I'm not ruling it in."
Asked if it could be a deal breaker Mr Key said he was not going to prejudge negotiations and said the Maori Party had a range of priorities. There were also a range of outcomes from the Maori Party abstaining on confidence and supply through to full coalition.
"Let's not prejudge things before we have an election."
