''Annette has been a wonderful deputy since I became leader,'' Mr Little said. ``She's tirelessly supported me and I've really appreciated her wise advice, humour and huge experience.
''She's also been an excellent health spokesperson. While I wanted her to stay in that role, I accept her reasons for wanting to retire. She has been an outstanding servant of the Labour Party and worked hard for a better and fairer New Zealand. She has made a huge contribution in government, opposition and in Rongotai.
''Caucus next Tuesday will vote for a new Deputy Leader. I will be nominating Jacinda Ardern for that position. She has performed extremely well as a list MP and her resounding win in the Mt Albert byelection is further proof that she has what it takes to be my deputy,'' Mr Little said.
Today's announcement comes after speculation Ms Ardern's showing in the weekend's Mt Albert byelection could see her elevated to the deputy position before September's general election.
It follows a week in which Ms King vehemently rejected any suggestion she would be replaced as deputy by Ms Ardern, saying suggestions it should happen were ``ageist''.
Ms Ardern's victory in the Mt Albert byelection had reignited talk about whether she should replace Ms King as deputy leader because of her Auckland base and high profile and to counter the change in National's leadership team to Bill English and Paula Bennett.
Mr Little said after the byelection there was ``no vacancy'' for the deputy slot and he wasn't ``planning any changes''.
Ms King said the decision to stand down was hers alone.
Any move to unseat her against her wishes would upset many in caucus, where Ms King commands a great deal of respect and influence.
Many MPs believed she should remain in the role where she was described as the ``glue'' that holds caucus together, alternating between being a supportive aunt to a principal reprimanding MPs who go astray.
The deputy role is chosen by a caucus vote but the leader's preference should have sway.
Ms King was initially appointed as an interim deputy for Mr Little to provide experience and a guiding hand as he settled into the role of leader in December 2014.
He had expected to appoint a new deputy when he did a reshuffle in October 2015.
Instead he opted to keep Ms King on until the election. At the time, Mr Little said Ms Ardern told him she did not want the role: ``The nature of the deputy's role is there's a lot of back office stuff that has to be done and that's been very important. Jacinda's strength is the outreach and getting out there, especially in Auckland where I need her to be most active.''
Ms Ardern said she had not put her hand up because she believed Ms King should remain in the role and her own focus was on trying to win the Auckland Central electorate in 2017.
That would have been her third attempt to get the electorate from National's Nikki Kaye, but Ms Ardern's Mt Albert byelection win has taken that out of the equation.
