Emergence services will be unaffected say service commissioners
Non-emergency ambulances in Cornwall and Devon may be operated by private companies in the future.
Those who commission ambulance services for the NHS want to put the work of transporting some 500,000 patients a year out to tender to save money.
South Western Ambulance Service NHS Trust (SWAST) fears the 999 service could be damaged as a result.
The commissioners say emergency services will be unaffected and new providers must meet NHS standards.
SWAST, which runs most of the non-emergency ambulances such as taking patients to hospital appointments, fears the 999 service will lose vital back-up in times of crisis.
But Steve Moor, director of commissioning for NHS Cornwall and Isles of Scilly said providers would have to meet "stringent NHS standards for conveying patients"
He said: "There should be no impact on emergency services."
A decision will be taken by the NHS Trusts' finance managers on 28 January.