Answer
Congress would have too much power over states.
Explanation
Federalism is a system of government where the power is divided between the national government and other governmental units. Thus the power is share between the federal government and other states as well as the local government.
Anti-federalists preferred a weak central government, This is because they equated a strong government with British tyranny. They had feeling that the states were giving up too much power to the new federal government. They sought to amend the Constitution, particularly with a Bill of Rights as a condition before ratification. This is because they feared that the constitution over-centralize the government and diminish the individual rights and liberties.
