Whangarei's mayor Sheryl Mai is appealing for people to dig deep and make sure the Hundertwasser project meets its funding deadline.
The trust fundraising for the $16 million art gallery still needs to find $3m by 30 June. It said it would not be easy.
Ms Mai said people should not assume the project was in the bag.
All donations, no matter how small, were crucial.
Prosper Northland plans to set up a crowd-funding appeal for the Hundertwasser centre as the June deadline looms.
Friedensreich Hundertwasser was renowned Austrian-born New Zealand artist and designer.
He built a bottle house in the Bay of Islands and designed the bright public toilets in Kawakawa.