But moving it will cost about $10 billion.
Add to that the complex social impacts, with transport infrastructure needing to change to support either decision, and jobs on the line in Auckland, Northland and the wider country.
For the latest Front Page podcast I talked to Simon Wilson about what the leak means, how this debate became so tense and fractured, and if there are any hints on what the Government will decide.
For the interview, listen to the podcast here.
If you have questions about Herald investigations, or want to stay up to date on social media, you can find host Frances Cook on Facebook here, Instagram here and Twitter here.
You can subscribe to this podcast on the podcast apps, including iHeartRadio here, Apple podcasts here, Spotify here, and Google podcasts here.