Labour has given an iron-clad guarantee the retirement age will remain at 65 if they get into power - making for a clear battleground for this year's election.
Prime Minister Bill English announced the Government's intention to legislate to increase the age of superannuation eligibility to 67 by 2040.
However, he didn't rule out ditching the policy in post-election negotiations.
The move has left National a party alone, with every other political party in Parliament against the move.
However, it has been welcomed by Retirement Commissioner Diane Maxwell, who called it a "step in the right direction".
Labour leader Andrew Little gave an assurance he would not touch the age, saying to have those working in physically demanding industries for an extra two years is unfair.
"I am absolutely and utterly committed to 65 as the age of eligibility, and that would be the basis of which, if we get the privilege of doing so, will run the country after September 23 this year," he told The AM Show's Duncan Garner on Tuesday.
Despite arguments people are living longer, Mr Little says the body "still wears out at pretty much the same rate".
"People doing physical work as part of their work now are struggling to get to 65 now, that's not going to change."
"The idea they should be required to work an extra two years or however long is just wrong and we won't be doing it."
When he ran for the Labour leadership, Mr Little opposed raising the age. He says the arguments haven't changed.
"I don't accept the assumption that somehow magically by 2041 it is unaffordable therefore you have to raise the age."
He says if affordability is the issue, the Government could start contributing to the New Zealand Super Fund which is hasn't done for nine years while in office.
Treasury's projected surpluses would be enough to fill the $20 billion hole in the fund, he says.
Mr Little says the Government's schedule for the legislation is "just crazy stuff" which will take effect after most current politicians have left office.
New Zealand First leader Winston Peters has made keeping the retirement age his bottom line.
However, he backs one part of the policy - the crackdown on eligibility for immigrants rising from 10 years of having lived in New Zealand to 20 years.
"Raising the residency requirements from 10 years to 20 years, which should be 25, that's a step in the right direction", Mr Peters told Newshub.
"In the last two years every time we've raised it in Parliament, they've said that we're scaremongering. They finally woke up."
But Mr Peters says it doesn't mean he'll definitely work with National because of their history of going back on their word.
"No one should take it seriously" Mr Peters told Newshub, saying National wouldn't follow through on the policy because "that's their track record".
Mr Peters also said the policy was "meaningless".
"This statement doesn't have any effect. There'll be barely anyone in Parliament, today, who'll be there then".
"If [Mr English] said three years from now, five years from now, people would listen to him. But he panicked".
The Maori party is also backing away from the policy. They want the retirement age to be lowered to 60 and won't support the Government's plan.
If Mr Peters decides not to back the age raise, he's not being honest with voters, Ms Maxwell told The AM Show on Tuesday.
"I don't know how he could say that we don't need any change, even in 20 years", Ms Maxwell told Duncan Garner.
"If you're saying that, you're not being honest with the voters, because we're living so much longer."
Ms Maxwell said that while she is pleased with the announcement, the 20-year roll out is a bit slow for her liking.
"I am really happy. Look, it's a first step in the right direction. I'd recommend a slightly quicker pace of change, but I'm comfortable."