Auckland mayor Len Brown has put a deal to the Prime Minister in a bid to get a downtown rail tunnel started in 2016, four years earlier than the Government intends.
Brown says waiting for the 2020 start already agreed by the Government will delay other important projects along the route and worsen disruption until the tunnel is built.
He has proposed to Prime Minister John Key that the council underwrite the Government's share of the project for up to four years. That would depend, however, on the Government agreeing to pick up half the full cost of the $2.8 billion project.
Brown says it was a discussion that really will need to take place over the next few months.
"The commercial sector are making decisions and in many ways they are now driving this project. Their investment is doing that - they believe it and see it."
The mayor said an earlier start would bring forward major plans by the private sector to invest in developments along the tunnel route and around new downtown stations.