What was the primary concern of the Anti-Federalists regarding the US Constitution?

The primary concern of the Anti-Federalists regarding the US Constitution was that it lacked provisions for a Bill of Rights. The Anti-Federalists were apprehensive that the Constitution, as initially drafted, did not guarantee specific individual liberties and protections against government overreach. They feared that without clearly defined rights, the newly established government could potentially infringe upon the freedoms of individuals and the rights of the states.

The call for a Bill of Rights was a significant factor in the ratification debates, as Anti-Federalists believed it was essential to outline fundamental rights such as freedom of speech, the right to bear arms, and protection against unreasonable searches and seizures. Their concerns led to the eventual drafting and adoption of the first ten amendments to the Constitution, collectively known as the Bill of Rights, which addressed these issues and helped to assuage fears about potential government tyranny.