“The Senate is now a national office rather than a state office”
I understand people’s trust in elected representatives over the masses, but this point has always bugged the crap out of me. To call it a state office is ridiculous. Senators exercise their authority with the best interest of their state at heart (hopefully), but it is the U.S. Constitution which imbues them with authority, and as such they are a part of the federal government (the Constitution being the document that gives power to the federal government).
When the constitution was drafted the Senate was intended to be a vehicle for the States to be represented. As such Senators were to be elected by the state legislatures. Thus while their office was a national office, their job was to represent the state and if they didn't do it, they would not be senators for long.
The founders set aside the Congress as a vehicle for the people to directly elect their own representatives. They then elected their state representatives who would in turn elect the Senators. The president was to be elected by "electors" chosen from the congressional districts who would go to the electoral college and pick a president.
It was a very good set up and ensured that the Federal Government would not become a "democracy" where the people of the United States could directly elect not only congressmen, but Senators and a President who would endure themselves to the masses by giving them money from the public largess.