Jacinda Ardern sets up 'zip it sweetie' battle of deputies

Jacinda Ardern's elevation to Labour deputy leader now sets up a battle of the deputies, with Ms Ardern to go head-to-head with National's Paula Bennett.

They've got history - a Parliamentary clash in 2012, when Ms Bennett told Ms Arden to "zip it sweetie".

National clearly thinks of Ms Ardern as a threat, with Prime Minister Bill English saying Ms Ardern is "untested". But she quickly fired back.

"He's been tested as Prime Minster before and that didn't work out too well," she said.

But make no mistake - she is about to be tested.

Andrew Little and Jacinda Ardern are Labour's new top duo and there's no secret here - they're out to grab the attention of voters.

With an election in six months and 22 days' time, there's no time to waste.

"We've got a good team ready to change the Government and I believe I've got what it takes," Ms Ardern said.

The raw truth is that she has what Mr Little doesn't - public appeal.

She's from Auckland, she represents a new style of politics - 'Jacinda' is a brand.

Her victory in the Mount Albert by-election gave the impetus for change but there was one problem - Annette King.

Just three days ago Ms King was going nowhere, with Mr Little firmly saying: "There is no vacancy."

Ms King even went so far as to say replacing her would be "ageist" and "sexist".

Now Mr Little says "there is a vacancy" but Ms King denies she was forced out, saying it was all her call.

And Mr Little claims there was no pressure at all.