National's deputy leader Paula Bennett will run the party's 2020 election campaign.
Mrs Bennett announced she would not contest the candidacy for her Upper Harbour seat, opting for a position on the party list instead.
National said campaign preparations were well underway, including candidate selections.
Mrs Bennett first took the seat of Waitākere in 2008 and narrowly kept it in 2011. After boundary changes it became Upper Harbour - a seat she won comfortably in the last two elections.
She said her full attention needed to be on the election campaign and the party now had the opportunity to look for a new candidate.
Cabinet Minister Megan Woods will be running Labour's election campaign.