Prime Minister Jacinda Ardern to apologise to Justin Lester for forgetting he ran as a Labour candidate

Prime Minister Jacinda Ardern will apologise to Justin Lester after seeming to forget he was a mayoral candidate for Labour.

In the weekend's local elections Lester lost the Wellington mayoralty to Andy Foster after serving just one term.

In her post-Cabinet press conference on Monday, Ardern was asked about Lester's failed bid, which was as a Labour candidate.

"Justin ran as an independent," she said, seemingly forgetting he ran on her party's ticket.

On Tuesday she clarified her comment, telling media she had wrongly assumed Lester ran as a Labour-endorsed candidate (as Phil Goff did in Auckland) and not on the party ticket.

"It's a very small difference, ultimately." 

She says he was backed by Labour, but "that didn't necessarily translate into branding and so on and that's where my error was made". 

That's despite Lester's campaign billboards and leaflets featuring clear Labour Party signage.

When asked if she intends to apologise to Lester for the blunder, Ardern said she has "no hesitation doing that". 

Lester doesn't seem too upset, telling NZME: "The PM has much more to occupy her mind than a local government campaign in Wellington."