Madison originally wanted the Constitution adopted "as written".
Later he modified his views and in the first Congress assembled under the new Constitution he proposed (in the spirit of compromise with New England) a list of amendments to the House of Representatives.
His proposal was ultimately crafted into the first twelve amendments by a House-Senate conference committee. Ten were quickly ratified becoming the "Bill of Rights". One was ratified in 1992 becoming the 27th amendment because a kid in Texas got P.O.ed at his college professor. The last one is still pending before the States.