"There's also a lot of commercial investors [that] need to have the confidence that the plan can be well executed, is well thought through and can be what Aucklanders want.
"It's the first opportunity to really see the team that they've put together. This is a substantial redevelopment of the Auckland landscape, particularly the CBD. You're retro-fitting an enormous piece of infrastructure."
With Civil Defence, Youth and ACC Minister Nikki Kaye, the Prime Minister was shown early developments in Auckland's underground system pegged for completion in 2023.
A number of issues are still to be ironed out at the Government's negotiating table, including the biggest question of how the $2.5 billion budget will be paid.
The council hopes the Government will stump up half the $2.5 billion cost, but a decision is still pending. Mr Key says a deal should be hammered out on how the bill will be split over the next 10 months.