The 17th amendment to the US Constitution is what broke Federalism. Originally the Senate was designed to represent a different constitutency than the House of Representatives, namely the states as political entities. By adding the 17th amendment to popularly elect Senators, we stripped the states of their voice in the government. When the state legislatures were represented in the Senate, the Senate would protect the States legislatures from encroachment of the federal government into the powers of the states. Now that the state governments no longer have a voice in the national government, they are effectively cut out of the decision making process which ensure that they will remain subservient to the national government rather than equal participants in the government itself. Since the states have been stripped of any voice on in the affairs of the national government since 1913, federalism has been weakened. If you want to save federalism give the state governments back their voice in the Senate and repeal the 17th amendment.
You are dead on. The 17th Amendment was a death blow to federalism and needs to be repealed.
There is a threshold question to every issue - before we decide, we must first establish and maintain the identity of those who should have the power to decide.