The political party formed to oppose the Constitution was called the Loyalists
Anti-Federalists Party
Federalists

Correct answer is Anti-Federalists Party.

Explanation:

Loyalist is not correct answer, because this was the term that was used for the colonists who were supporting Britain during the Revolutionary war.

Anti-Federalist Party is the correct because this party was opposing the Constitution, in contrast to Federalist Party which was supportive of the Constitution.

Anti-Federalist party

Explanation:

During the debates for the ratification of the new U.S. Constitution (1787), two political parties emerged: First The Federalist party which was led by Alexander Hamilton and other leaders (mainly bankers, northern businessmen, and merchants) that supported the idea of a strong central government and the ratification of the newly proposed Constitution (1787), and secondly, the Anti-Federalist party which was formed to oppose the ratification of the Constitution as well as many other Federalist's ideas.

Overall, the Anti-Federalists, led by Thomas Jefferson and James Madison and consisting mainly of planters, small farmers, and artisans, leaned to give more power to the states and opposed the establishment of a strong government as well as the ratification of the Constitution arguing that it did not contain a Bill of Rights. They believed that without a Bill of Rights that protected people's liberties and put limitations on the government, the latter would eventually abuse its power.