Former Prime Minister Sir John Key has come out backing National's Emma Mellow for the Auckland Central seat.
The three frontrunners for the seat are Mellow, Labour's Helen White and the Greens' Chlöe Swarbrick.
Key said in a video on Twitter it is his "great pleasure" to support Mellow.
"I first met her in 2008 [on] election night - great night for the National Party and for me personally when we had the chance to lead the country," he said.
"And Emma was part of a group of very enthusiastic supporters. She did an amazing job for the Young Nats, worked really hard for them.
"Of course, she's gone on to have a great corporate career. She's at ANZ - I happen to be chairman. I'm not going to be biased but I'd really like to accept her resignation and allow her to have a career in Parliament as the MP for Auckland Central."
The Auckland Central seat was held by outgoing National MP Nikki Kaye for 12 years.
A Q+A Colmar Brunton poll released on Sunday shows there's potential results could be tight in the electorate.
White is in the lead on 35 points, Mellow is second on 30 and Swarbrick is on 26.
These results make it a closer race compared to a Newshub Nation-Reid Research poll done last month, which had White on 42, Mellow on 26 and Swarbrick on 24.