It was related to the way in which population would be counted in each state.
Take Care ^-^
The Anti-Federalists were most concerned with the fact that the Constitution was giving far too much power to the central government over the states--meaning that they feared the federal government would become tyrannical.
There are too many citizens for each of their interests, ideas and opinions to be heard and taken into account one by one. a representative can take the majority vote of the people and refer it back to the higher power.