The Public Service Association says its members overwhelmingly oppose a proposal to amalgamate Northland's councils.
The PSA has presented its submission to the Local Government Commission on the draft plan for a unitary authority in Northland.
The proposal has a single council replacing the current four councils in the region.
The PSA represents about 200 workers throughout the councils.
Its acting national secretary Glenn Barclay says there isn't enough evidence to show amalgamation would bring significant benefits to the people of Northland. He says members are also worried for their jobs if amalgamation goes ahead.