What was the main reason that the framers created federalism

The Framers chose federalism as a way of government because they believed that governmental power inevitably poses a threat to individual liberty, the exercise of governmental power must be restrained, and that to divide governmental power is to prevent its abuse.

Federalism: is a system of government in which a written constitution divides the powers of government on a territorial basis, between a central government and several regional governments, usually called states or provinces.  

This system of government is set out in the Constitution. Both the national and state governments have their own separate powers.

Federal Powers: Delegated powers, expressed powers, implied powers, and inherent powers.

whose power in the senate is equal to the power of the speaker of the house?