In a shocking twist, ex-Senator Fred Thompson has joined the effort to abolish the Electoral College. He claims that the National Popular Vote movement is “totally consistent with our constitutional principles.”

I like Thompson. I voted for him in the 2008 presidential primaries. But his endorsement of NPV simply cannot be reconciled with the Constitution. It is a pity, because he has spent so much of his public life defending these important principles. It is puzzling that he has abandoned them now.

NPV is consistent with the Constitution?

The delegates to the Constitutional Convention explicitly rejected a nationwide popular vote for President. The small states would never have ratified the Constitution with such a system in place, for fear that they would be constantly outvoted by big states such as Virginia and New York. NPV implements the system that was rejected and pretends that it is somehow consistent with this constitutional history.

The Constitution requires approval from three-quarters (38) of the states before radical change can be made to constitutional processes. NPV is on track to change the method of electing a President with the approval of fewer than 20 states.

The Constitution implements a system that combines the best elements of federalism, republicanism, and democracy. The Founders understood from their study of history that a pure democracy “is one of the greatest of evils” that “soon wastes, exhausts, and murders itself.” It is “very subject to caprice and the madness of popular rage.” NPV shuns the lessons of history—so important to the Founders—and replaces America’s federalist, republican, democratic presidential election process with a purely democratic one.

There is more: NPV will likely cause Equal Protection, legal and logistical problems that I have discussed at length elsewhere. But even these few examples should show that Thompson and others need to more thoroughly study the history of our Constitution and the Electoral College before casually claiming that NPV is consistent with America’s founding principles.

The balance of power between state and national governments was one of the most contentious issues for the American Founders.

The states were important historically, but also as a way to keep government close to the people and to divide government power into as many hands as practical in order to preserve liberty.

At the Constitutional Convention small states wanted every state to have an equal voice in the national government. Large states desired just the opposite—representation based on population would give them more power.

It was a compromise that created the U.S. Congress, where states are represented equally in the Senate but according to population in the House. That compromise not only broke the deadlock that threatened to derail the Constitution—it became the foundation for the unique American system of Federalism.

The national government was set up to provide national defense, manage foreign trade, and referee disputes between the states—in short, to provide the states with safety and commerce similar to the way the British Empire did for the 13 original colonies. The states were left to manage their internal affairs and to compete with one another; thus the states are sometimes referred to as our “fifty laboratories of democracy.”

Federalism fosters diversity by allowing groups of people in different states to manage their affairs differently, to innovate or remain the same, to address local needs. And by keeping government local, dividing it up, and making it compete, Federalism protects freedom.

The American system of states is not just unique—it has been uniquely successful. Federalism is an American invention worth preserving.