Ambulance managers have told Health Secretary Patricia Hewitt they have "grave doubts" about plans to create a giant regional service.
The chairman and chief executive of Staffordshire Ambulance Service expressed their concerns when they met Ms Hewitt in her London offices.
But speaking after the meeting, they said the Health Secretary asked them to press ahead with plans for a merger with the four other ambulance trusts in the West Midlands.
Robert Lake, chairman of the ambulance trust, and chief executive Roger Thayne, were accompanied by Staffordshire MPs David Kidney (Lab Stafford), Charlotte Atkins (Lab Staffordshire Moorlands) and Janet Dean (Lab Burton).
A spokesman for Staffordshire Ambulance Service said: "She [Ms Hewitt] accepted that the people of Staffordshire must not have a lowering of standards as a result of reorganisation and that any proposals must guarantee that the present standards in Staffordshire are maintained.
"She stated that her preference is for a regional ambulance service working alongside regional police and fire services.
"She has requested that Staffordshire Ambulance Service work closely with the other West Midlands Ambulance Services to form a regional ambulance service which maintains Staffordshire's standards while improving the region as a whole.
"While we agreed to work to see whether such a regional ambulance service could deliver high performance we expressed our grave doubts that reconfiguration and reengineering should be attempted at the same time."