Current reliable multicast protocols do not have scalable congestion control mechanisms and this deficiency leads to concerns that multicast deployment may endanger stability of the network. In this paper, we present a sender-based approach for multicast congestion control targeted towards reliable bulk data transfer. We assume that there is a few bottleneck links in a large scale multicast group at any time and these bottlenecks persist long enough to be identified and adapted to. Our work focuses on dynamically identifying the worst congested path in the multicast tree and obtaining TCP-friendly throughput on this selected path. We use the network simulator (NS2) to validate and evaluate our congestion control algorithm with both drop-tail and RED gateways.