Andrew Little drew on his successful battle with prostate cancer eight years ago to paint himself as a fighter who can overcome the odds to become the next Prime Minister, in a speech to a joint Labour and Greens rally in Auckland.

"I've faced tough fights before. And this is one fight we simply have to win," the Labour leader told a packed hall in Mt Albert, where a byelection will be held on February 25.

"This isn't going to be an easy fight. It is going to be close, it is going to be tough."

READ MORE: Audrey Young: Little shines at state of nation rally


Early in his speech, Little went into graphic detail about the battle and recreating the uncertainty it had brought to him and his family.

The only reason he had caught it was because his wife, Leigh, a former nurse "had a hunch.

"I remember sitting at my kitchen table thinking about my family, about the future, about my wife, Leigh, and my son, Cam.

"It made me think about seizing opportunities, about making the best of this life.

"My battle with cancer colours everything I see, even today."

LISTEN: Andrew Little speaks to Andrew Dickens

It gave him a stronger determination to strive for a system that is genuinely fair for everyone."

He continued with the family and personal theme in his attempts to highlight housing affordability problems.

There was a good chance that Cam, who will turn 16 this year, and his generation would never own their own home.

"I want my son and his friends to have every opportunity I had. I think every parent feels the same way.

"That's why I'm so determined to fix this housing crisis."

Both he and Greens co-leader Metiria Turei, who spoke ahead of Little, criticised new Prime Minister Bill English.

Turei said "now we have a Prime Minister who believes Government can do no more, a Prime Minister who won't end poverty, a Prime Minister who is the architect of the housing crisis, a Prime Minister who accepts locking out an entire generation from warm, safe and affordable housing."

National might do what was easy but it would not do what was right.

"The Greens will do what is right, even when it's not easy."

Little said the country got a new Prime Minister but not a leader.

"He should be at Waitangi next weekend, representing all the people of New Zealand on our national day but he won't be," he said.

"He should be here in Mt Albert, making the case for his Government in the byelection. But he isn't.

"He should have fired the failed housing minister, his friend Nick Smith, but he didn't."

Neither Little nor Turei released new policy but emphasised existing policy and their own values.

Turei made strong references to women who had inspired her, in particular the former union leader the late Helen Kelly, and former Greens co-leader Jeanette Fitzsimons who was among grandmothers last week who chained themselves to one of Fonterra's fences in protest at the company's use of coal.

Referencing US President Donald Trump, Little said there had to be a better path than isolation and bigotry.

"It's our turn to shine and to lead the way, to be New Zealand at its best.

"New Zealand can be a beacon to the world."

Little said together the Labour and the Greens were committed to building a better New Zealand.

"We are ready to win. We are ready to govern."