The museum had half of the money needed and was "confident" it could raise another $10m. That left a funding gap of $70m.
"The museum is in active discussions with other possible funders and has developed a business case seeking funding from central government to secure the funding shortfall," said Wright.
"The redevelopment is urgent. If it does not happen, we may be forced to consider options for closing public sections of the buildings to store and protect the collection."
Concept designs had been developed by Athfield Architects.
The museum was asking the council to publicly notify the resource consent so everyone had an opportunity to comment on the plans.