Anti-Federalists believed the Constitution would keep elites in power, endanger liberty especially for individuals, and weaken the states.
The Articles of Confederation, in place prior to the ratification of the Constitution of the United States of America, had granted stronger authority to the states. Patrick Henry and other Anti-Federalists were concerned about too much power winding up in the hands of the federal government and its executive branch, thus allowing a small number of national elites to control the affairs of the USA. They feared this also would diminish the rights and freedoms of individual citizens.
The Bill of Rights, laid out in the first ten amendments to the Constitution, provided some reassurance to Anti-Federalists after the fight over ratification. The US Constitution was ratified in 1788. The Bill of Rights was created in 1789 and ratified in 1791.