The second, even more important, function served by senators, was as representatives of their state or commonwealth government to the federal government in Washington. Whereas a representative from Dubuque or Des Moines would be voting the whims of their respective constituencies, the senator from Iowa was expected to represent the sovereign interests of the Hawkeye State. This has very specific effects on the separation of powers in the U.S. Constitution.
I’ve been saying for years that the 17th Amendment is an abomination. It means we effectively have two Houses of Representatives. The State governments have no representation when Senators are elected by the people at large. Do you think that any sovereign State would vote unfunded mandates on itself?
Source: Decline of the Republic Day