The Constitutional Convention of 1787 was made up of delegates from the States as formed by the Articles of Confederation. It is evident from the journal of the Convention and notes of delegates including James Madison that the delegates fully debated and understood the difference between a national and a federal government. In the final document,they soundly rejected a national government. The Constitution was written to form a more perfect union of States. Thus, this father of the Constitution confirmed that the States were the contracting parties between themselves.
States are the characteristics and soul of a confederation.
If the states are not the agents of this compact, it must be one great consolidated government, of the people of all the states. The people, to be sure, said Madison, were parties to the compact, but not the people as composing one great body. Rather, it is the people as composing thirteen sovereignties. But, sir, no state is bound by it, as it is, without its own consent. The Electoral College is an example of the fact that the Constitution established a federation of states, not a majority-rule national government.