Which president is often called the father of the United States Constitution?

James Madison, the fourth president, is commonly referred to as the Father of the Constitution, because of his work in bringing about the adoption of the Constitution. He drafted much of the "Virginia Plan", brought about the compromises between the different states and had a hand in writing much of the document itself. Without his efforts in creating a constitution that all states could accept, the Constitution probably would not have been adopted and proposed for ratification. In addition, once the proposed Constitution was under consideration by the states, Madison, with Alexander Hamilton and John Jay wrote a series of articles each called "The Federalist" which advocated ratification of the Constitution.