Senators campaign; who does the work?

As the primary election is finally coming to a close, I have an important question to anyone who can give an honest answer:

Our three senators have had a busy 15-month hectic schedule.

Since they must be absent from Washington, who represents the constituency back in the senator's state?

Who are these people? Don't we have a right to know? No one can do both jobs at once.

Is it possible to have more information regarding this? Who is paid to do this work while the senators are campaigning and I wonder how much that would be?

Perhaps the stand-in should run for the senator's position at election time.

Marge Carrison

Schaumburg