When it was suggested Ardern's Auckland base was one, King replied "does it really matter these days?" and said she could travel the country as a list-only candidate.
When former Prime Minister Key set out his preference for Paula Bennett to be deputy to Bill English, it was not because he enjoyed her witty conversation.
It was because National polls the bejeezus out of everything and he knew those polls showed Bennett had a cut through in Auckland - the juggernaut of votes - that other ministers did not.
Ardern's Auckland base, her ability to communicate well from children to Auckland business leaders, her popularity and her deft touch with 'soft' media make her an asset Little could better utilise by having her as his deputy.
It is an asset he cannot afford to ignore.
King's value to Little is indisputable but largely for internal reasons - she is in Wellington to run the ship while he travels the country and can control caucus with one pinky finger.
But Ardern's value is external - and in an election year that is the greater need.
King remains valuable for Little, not least because of her ability to control caucus. But his need now is votes - not a guiding hand.
If Little does make the switch, it will be when he does a mini-shuffle to slot Raymond Huo into the caucus.
The trouble is he cannot risk replacing her now King has publicly stated her wish to remain in the job.
Little could take the risk of upsetting the likes of MP Poto Williams and Maryan Street over his decision to recruit Willie Jackson to Labour, but he can not afford to get offside with King.
King has great loyalty in Labour and Little will not be able to replace her unless she recognises it is a necessary idea herself.
He somehow has to make it seem like it was her idea all along.
And that is now too late. Ardern would likely refuse if King was upset by it.
Then again, Little has already shown his eye is firmly on doing what he has to do to win in 2017.
It showed when he recruited Willie Jackson and then managed to get Maryan Street to step aside to allow Huo - who was more important to Little strategically - to get back into Parliament.
Little may well have to drag some in his party kicking and screaming to get there - but he's made it clear that's not going to stop him.
He's asking them to trust his judgment. That's fair enough as it will be his head on the block - not King's - if he fails in September.