A decade after the federal government plunged into the financing of health care, it has emerged not only as the system's major purchaser, but also as the major influence on health policy directions of the future. The traditional Washington dictum of "he who pays the piper calls the tune," is becoming a reality in health care, albeit not without a struggle. As a result, the new administration of President Carter will have to confront a range of difficult health issues and decide how best to balance the conflicting forces that call for different answers.