The Fire Brigades Union has called on the government to scrap plans to close 46 emergency call centres.
The union fears the changes will affect standards
They are to be replaced with nine state-of-the-art regional centres in England at a cost of £1bn.
Ministers argue the changes would make the service more able to deal with major incidents such as natural disasters and terror attacks.
But the FBU argues that the money would be better spent on staff, training and equipment.
It says a survey of almost 2,000 of its members showed almost everyone believed the plans would damage the fire service's ability to respond to incidents.
FBU general secretary Matt Wrack, told the BBC they were concerned about the effect on the fire and rescue service.
"We think that there will be a worse service, that there will be a loss of the local knowledge and skills that those emergency fire control staff bring to the fire service.
"There are concerns about safety, about the ability to deal with the local detailed information that would be required."
But a spokesman for the Communities and Local Government Department defended the centres.
"In today's world of industrial accidents, terrorist attacks and large-scale natural disasters we need to build resilience at national, regional and local levels. Given these threats, doing nothing is not an option."
He said the government was committed to delivering the scheme on time and on budget.