The federalists gained the necessary support for the constitution by?

Anti-Federalists argued that the Constitution gave too much power to the federal government, while taking too much power away from state and local governments. ... In part to gain the support of the Anti-Federalists, the Federalists promised to add a bill of rights if the Anti-Federalists would vote for the Constitution.

the virginia plan called for three branches of government and two houses of congress. representation in each house would be determined by population. the new jersey plan called for three branches of government and a single house of congress. each state would have an equal vote.