Jane Dodds fears that fire services in rural parts of mid Wales are unsustainable “if things carry on as they are”.
The Mid and West Wales MS said at the Senedd that the problem has been highlighted by the chief fire officer.
She said the service in her constituency is staffed in the main by retained firefighters supported by whole-time staff.
But the service is finding it increasingly difficult to recruit and retain firefighters.
Ms Dodds said: “It's clear that the offer in terms of pay isn't commensurate with the number of hours they work — some of them around 120 hours.”
She called for the Welsh Government grant to be reviewed so that fire services can make necessary increases to the retained firefighter service.
Deputy Social Partnership Minister Hannah Blythyn said she recognises that for many communities, retained fire services provide much-needed and valued cover.
But she said the Government doesn’t directly fund fire and rescue authorities so wouldn't fund them directly for core services.
She said she is looking at what can be done to address that challenge.