In this paper, a new power aware many-to-many routing protocol for wireless sensor and actuator networks is introduced. The protocol has two versions adapted for three cases. The first version is designed for networks where every node transmits at the same power level. The transmission power level may not be adjustable, or can be adjusted according to a deployment scenario and changed before or after the deployment. The second version is for the case where nodes can individually adjust the transmission power according to the channel conditions and communications distance.