Councils north of Taupo are considering an agreement that would see them co-operate more closely in areas such as transport and roading.
Auckland Council and Waikato, Bay of Plenty and Northland Regional Councils cover more than half of the country's population.
Their economies are inter-linked in many ways and the councils say they have common issues such as roading, transport and infrastructure. Three also have their own ports.
Auckland Mayor Len Brown says it's not about creating a super-region, but closer co-operation that works in the country's interests.