Auckland's rural councils say their districts could lose their individual identities if a super-city is recommended for the region.
The Government is to receive a report on Wednesday on the Royal Commission on Auckland Governance, which will recommend how to reform the region's councils.
Auckland is administered by seven local councils and a regional council which, critics argue, needlessly wrap the city in red tape.
The report's contents have been closely guarded, but a super-city combining all eight councils has been one of the options suggested.
The Rodney, Franklin and Papakura district councils are part of the greater Auckland region, but are mainly rural.
Papakura Mayor Calum Penrose says smaller councils work better
because they are more in touch with ratepayers.
Auckland's seven mayors remain deeply divided on how the region should be run.
Auckland City Mayor John Banks says he wants a super-city to encompass the whole region, but North Shore Mayor Andrew Williams says that would be a monstrosity and leaders would be out of touch with the people they represent.
Prime Minister John Key expects the report will be made public within a few days.
Mr Key says he does not know what the report contains, so it could be some time until the Government comes up with a detailed response to the recommendations.
However, Mr Banks, along with several other mayors, says it would be flawed for the Government to hang on to the report, and should release it immediately.