The National Popular Vote (NPV) interstate compact proposes to change the presidential election system from a state-based federal system to a national popular vote system. NPV proponents contend states can implement the compact without federal governmental authorization. This article addresses the constitutional questions of whether the NPV must obtain Congress's approval and whether Congress has the constitutional authority to grant such approval. In addressing these questions, I review U.S. Supreme Court precedents and constitutional history and find the NPV is the type of compact the Supreme Court would conclude requires congressional approval. Most importantly, I contend Congress is constitutionally unable to grant approval of this compact and the Supreme Court will play an integral role in making this determination.