The Articles of Confederation
Before the Constitution, there existed another document that acted as the law of the land - the Articles of Confederation. The Second Continental Congress signed the Articles of Confederation in 1777. It established a government dominated by the states. There was one house in the legislated branch, with each state having one vote. They "overcorrected" the unitary British government to a confederation, where there was virtually no national power.
Failure of Congress
Because the National Government had no power, it couldn't make the states do anything. States attended congressional meetings haphazardly. Congress had few powers outside maintaining an army and navy- and little money to do that. It had to ask for money from the states, because it had no power to tax. If states didn't send any money, they didn't have any. In desperation, Congress sold off western lands to speculators and did many desperate things just to get enough money to function. They had no power to regulate commerce, and that inhibited foreign trade and the development of a strong national economy. Overall, it was very weak, and it was quickly abandoned after 8 years.