Preseli Pembrokeshire AM Paul Davies is campaigning to keep Pembrokeshire's Town Rider service on the move.
The dial-a-ride service, which operates in five county towns, runs out of funding this month. Mr Davies is now lobbying the Welsh Assembly Government to continue supporting the service which has provided nearly 10,000 passenger journeys in the past year.
"More than 500 people, most of them aged over 80 and all with mobility issues, rely on the excellent service provided by the Town Rider scheme," he said.
"We have an ageing population and this is a valuable resource that gets plenty of use, it would be a terrible blow if it had to come to an end due to lack of funding."
A number of residents have written to Mr Davies expressing fears that the scheme may be cut and Pembrokeshire County Council, who developed the scheme alongside the Pembrokeshire Association of Community Transport Organisations (PACTO) are also pressing for continued funding.
"I have written to Ieuan Wyn Jones the Welsh Transport Minister to urge him to consider committing to a long term funding plan for the initiative.