Why did Thomas Jefferson form the Republican Party?

Thomas Jefferson formed the Republican Party (often called the Democratic-Republican Party) primarily to prevent the national government from becoming like a monarchy. He was concerned about the concentration of power in the federal government and the potential for it to resemble the hierarchical structures of European monarchies, particularly in response to the policies of the Federalists led by figures like Alexander Hamilton. Jefferson and his allies advocated for a strict interpretation of the Constitution, state sovereignty, and greater power for the common people, countering the Federalist vision of a strong central government.