Final answer:
James Madison was the principal author of the U.S. Constitution and played a significant role in its formation. He also served as the 4th President of the United States.
Step-by-step explanation:
James Madison was the principal author of the U.S. Constitution. He played a crucial role in the formation of the Constitution as an important participant in the Constitutional Convention and authored many of The Federalist Papers. Despite his initial skepticism, Madison wrote a Bill of Rights to address concerns about the federal government's power. He also served as Thomas Jefferson's vice president and was later elected as the 4th President of the United States in 1808.
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