Community groups are joining forces to fight plans for 2,500 homes in a Mid Sussex market town.
Six associations have come together to block proposals which would increase the size of East Grinstead by a third.
The East Grinstead Post Referendum Campaign believes West Sussex County Council's plans represent massive over-development.
Its launch today follows a referendum in June this year when 96 per cent of voters rejected the council's draft structure plan.
The vote was held by the town council after residents pushed for a say on plans which were first mooted last year.
Under the county council's plans, more than 2,500 houses would be created on the west or south-west of East Grinstead and a relief road built.
The new road would cut through the High Weald Area of Outstanding Natural Beauty.
Campaigners now want to make sure the proposals are rejected and have started lobbying councillors.
Joint chairman of the campaign Garry Turvey said: "Having spoken so clearly, East Grinstead's people expect action to follow.
"Plans for unsustainable expansion must be dropped. That is the purpose of the Post Referendum Campaign.
"We have all come together to see the people's expressed wishes are carried out."
Tony Lane, also joint chairman, said he wanted all the authorities concerned to drop "unsustainable expansion".
He said: "There must be a strategy for incremental development, respecting East Grinstead's character as a market town.
"And of course the alternative strategy must be submitted to the approval of East Grinstead's electors before adoption.
"If the councils agree to do this, the campaign will be offering all constructive assistance."
The groups involved in the campaign are: Association of Imberhorne Residents, Forest Row Association, Crawley Down Residents' Association, Protest Against Road Outrage, East Grinstead Society and Three Counties Group.
A West Sussex County Council spokesman said amendments had been made to the draft structure plan, which would be published before a full council meeting on November 28.
He added: "The amendments follow a previous consultation exercise and will themselves be subject to a six-week consultation programme at the beginning of next year."
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