Preseli Pembrokeshire AM Paul Davies is lobbying for the planned "super‐surgery" in Milford Haven to go ahead.
He is writing to Welsh Health Minister Edwina Hart to ask her to make an exception to the Welsh Assembly guidelines which have ruled that the planned facility will be too big.
It was hoped the new Milford Primary Resource centre in Manchester Square would house the Robert Street and Barlow House GP practices. But a change in Welsh Assembly guidelines means the new centre was refused for being too big and there is now a shortfall in funding.
"This is the ideal site for a much‐needed new facility and it is crazy that red tape is preventing it from going ahead when every other piece of the jigsaw is in lace," said Mr Davies.
"I am in touch with the Local Health Board about the issue and not all hope has been lost.
"I shall now be lobbying on their behalf for the rules to be relaxed in this one instance as it is a perfect solution for Milford Haven."