The fire and rescue service in England has proposed taking over and running the ambulance service.
Peter Holland, president of the Chief Fire Officers Association (CFOA), says the idea could save money and improve the service with faster response times.
The CFOA says the ambulance service is struggling to meet its response targets of dealing with 75% of life-threatening calls within eight minutes.
But an ambulance official says the idea would not be workable.
Mr Holland says: "We are calling on the Department of Health (DoH) and the Department for Communities and Local Government (DCLG) to review this idea.
"By basing fire and ambulance stations together we could generate savings for the future."
Figures for 2009 to 2010 show that five out of the 12 ambulance services in England are not meeting the 75% target.
The CFOA believes it could respond to life-threatening calls within eight minutes 90% of the time.
The fire service is only interested in running the emergency response section of the ambulance service, suggesting the patient transport service could be left with the NHS or run privately on the open market.
Chief fire officers will be making the case to run the ambulance service at the Conservative party conference in Birmingham next week.
It is unlikely to go down well with unions. Jim Petter from the College of Paramedics, the ambulance service professional body, says: "Culturally the two services are very different. I just can't see how it would work.
"The ambulance service went through a massive reorganisation in 2006 when the 29 ambulance services in England were cut to 12. Changing it again would only be damaging."
Jo Webber, director of the Ambulance Service Network - representing the services, says: "It is hard to see how the fire and rescue service think they could improve things.
"We deal with a huge number of calls compared to the calls to the fire service.
"We are already improving response times by building up a big network of community paramedics based in doctor's surgeries.
"This idea would mean a massive reorganisation which I just don't think would be workable."
The Ambulance Service Network also believes the move could be motivated by fears over fire service funding, which comes from the DCLG.
A paper leaked to BBC Radio 4's You and Yours says: "While spending in the Department of Health has been ring-fenced from Treasury spending cuts, the Department of Communities and Local Government is facing cuts of between 25 and 40%".
A DoH spokesman said: "The department has had discussions with DCLG about options for operational efficiency in each service but there are currently no plans for any kind of merger."