Labour's deputy leader Kelvin Davis said he won't be seeking the role of deputy Prime Minister but he wants to stay on as Labour's leader.

Davis said Labour has a "very big caucus" and said his role of deputy, would be one of supporting the wider caucus.

He said Jacinda Ardern offered him the role of deputy Prime Minister ahead of the election.

But Ardern said that it was a decision that was up to him.

Davis would not say who he was supporting to be the deputy Prime Minister.

But he would not go into caucus matters, including who will get what portfolio.

Ardern said Davis told her before the election that deputy Prime Minister was not a role he wanted.

"Kelvin has made this decision, he still has my full confidence."

He has Ardern's "full support" to be the part's deputy leader.

She said there was no reason why he can't be deputy labour leader and not deputy prime minister.

"It's a role he wants to stay on with."

She wouldn't say who she wants to stay on a deputy Prime Minister.

She said her "complete focus" was building her team.

"This has been Kelvin's decision," she said, adding that it's one that she respects.

On the vote, Ardern said every minister is going to be voted on this morning.
Anyone is able to nominate and there will be a vote "if required".

Ardern said she has talks with the MPs beforehand, so it's not a surprise.

"We do work through a bit of a consensus process."

Ardern fronted media before a caucus vote on which MPs will become ministers in her new Cabinet.

That meeting will include a confirmation vote on the party's leadership.

Ardern and the deputy leader need at least 60 per cent support in the confirmation vote; if not, a leadership process is triggered.

Ardern is certain to win the vote.

Chris Hipkins said whether or not he takes on the health portfolio is up to the Prime Minister.

He said he would "love" to continue being a Minister - it's a privilege he said he thoroughly enjoyed

Finance Minister Grant Robertson told media that he has nothing to say about the deputy leadership.

"We don't talk about what happens in caucus."

Former Health Minister David Clark said whether or not he is back in a high-ranking cabient position is up to the caucus.

Davis is the current Deputy Labour Party leader, but he had so far been unwilling to comment on whether or not he would like to be the Deputy Prime Minister.

That role was vacated by NZ First leader Winston Peters, after his party failed to reach the 5 per cent threshold at the election.

That means he's out of Parliament and Ardern's Cabinet.

Ardern has previously said Labour's Deputy Leader will take on the role of Deputy Prime Minister.

But, speaking to reporters yesterday, Davis wouldn't be drawn on whether he wanted to stay in the job and become Deputy Prime Minister.

Ardern was also not giving anything away. When pressed on the issue, she compared it to a "not very fun pub game".

"I will not be entertaining any speculation," she said.

As well as the leadership vote, Labour's caucus will also vote on ministerial positions. It is understood Ardern is going to take the lead on nominating MPs for various positions.

There are a number of vacated roles in Cabinet that Ardern needs to fill.

There are six empty seats at the Cabinet table: those vacated by the four NZ First ministers, and the unfilled vacancies of former Labour Party ministers Iain Lees-Galloway and Clare Curran.

Finance Minister Grant Robertson is expected to be given Infrastructure so he can oversee the roll out of the $12 billion NZ upgrade programme and the $3b shovel-ready fund.

Yesterday, Ardern gave nothing away over whether Chris Hipkins would keep Health, Education or both, or continue with parts of either.

Ardern said she wanted to balance expertise and experience with caucus talent.

That could include promotions for, among others, chief whip Michael Wood, junior whips Kiri Allen and Kieran McAnulty, and former primary school principal Jan Tinetti.

Cabinet usually has 20 ministers, and Ardern said the size of the executive would be largely unchanged.