Paramedics lobbied MPs to highlight their fears for patient safety at Yorkshire Ambulance Service (YAS).
The Unite union is in dispute with ambulance bosses over claims that patient safety is being compromised by £46m in budget cuts over the next five years.
The union claims plans to send semi-skilled emergency care assistants to 999 call-outs will leave patients at risk of poor care.
Unite has also been de-recognised by YAS for collective bargaining on behalf its members.
Last week shadow health secretary Andy Burnham addressed the MPs at the Westminster lobby.
Rachael Maskell, Unite’s head of health, said: “The lobby is designed to highlight the very real concerns that we have about patient safety in Yorkshire as what the trust proposes means the removal of a number of skilled technician staff from ambulances.
“They are being replaced by emergency care assistant roles (ECAs) who are being given only six weeks training – only half of which is in clinical skills.”
Bosses at YAS have denied that safety is being compromised, saying their plans will increase the number of trained paramedics over the next five years.
They said in a statement: “During this period there will be a broad range of fully-funded training opportunities for 450 staff to become paramedics, with the ultimate aim of having a paramedic on every frontline emergency vehicle.
“The ECA is a well-established role used in the majority of other ambulance services to deliver an appropriate level of support.”