A consultation on the merger of ambulance trusts in England was a waste of time, the chairman of Lincolnshire's trust has said.
The Lincolnshire service will merge with its neighbours
Linda Honey said she cannot see any point in merging the service - which will join the trust serving Notts, Leics, Northants and Derbyshire.
But Lincoln MP Gillian Merron insists the change will bring faster response times and improved the service.
Government minister Lord Warner announced the merger on Tuesday.
Mrs Honey said: "Big is not always beautiful - the ambulance service has consistently shown its ability to modernise, meet its targets and maintain financial balance over past 15 years.
"I am a loss to see the point of the consultation process as the majority of the respondents from across the East Midlands were against the proposals."
Boston MP Mark Simmons has also said he could not understand why the government did not listen to local objections to the scheme.
But the chairman of the East Midlands Ambulance Service (EMAS) Chris Faircliffe said he was looking forward to sharing good practice with colleagues from Lincolnshire and Northamptonshire.
Lord Warner said: "By creating fewer larger ambulance trusts, there will be less bureaucracy, more money to invest in front line services and better care for patients.
The boundary changes that were recommended will create larger organisations that will be better equipped to meet the challenges faced by a 21st Century service."
"We know that these changes are important for local people, which is why we put the proposals to public consultation.
He said the larger trusts will mean more investment in front-line services and improved patient care - and there would be no reduction in ambulance vehicles or front-line staff.
East Midlands Ambulance Service has covered the counties of Leicestershire, Rutland, Derbyshire and Nottinghamshire since 1999.