Is it the defendant or plaintiff that has the right to waive a jury trial in a civil case?

Who holds the right to wiave the jury trial and upon what is it based? (US constitutional law)Is it the defendant or plaintiff that has the right to waive a jury trial in a civil case?
In a CIVIL case, the laws of the states vary with regard to waiving jury trials. In general, consent of both parties is needed.Is it the defendant or plaintiff that has the right to waive a jury trial in a civil case?
The defendant. It is a practice of law and not a regulation, statute or code.
The Constitution guarantees an accused person the right to a trial by a jury. If you are the accused person, that is the Defendant, only you can waive that right.
Defendant. He has the right to a jury trial, and also the right to waive that right.