The American two Party Political System Since the administration of George Washington two political parties have dominated the United States political system, but they have not always been the same two parties. The first two parties were the Federalists and Anti-Federalists. Federalists were those who supported a strong federal government and the Anti-Federalists were those who did not. The leaders of the Federalists were Alexander Hamilton and John Adams. Both were from the Northeast where the Federalist line of thinking was strongest. Thomas Jefferson became the leader of the Anti-Federalists. These two groups