Thomas Jefferson was an active Anti-Federalist as he feared that a strong central government would result in another Monarchy.
Anti-Federalism was a movement that against the creation of a stronger U.S. federal government and they later opposed the ratification of the 1787 Constitution. The previous constitution gave state governments more authority. Anti-Federalists worried that the position of the president might evolve into a monarchy. Anti-Federalists helped with the passage of the United States Bill of Rights.