Senior Senator an Junior Senator are terms commonly used in the media to describe United States Senators. Each state sends two senators to serve in the Senate; the longer (continuously) serving of the two is by convention referred to as the "senior" senator, and the other is referred to as the "junior" senator. If both are elected at the same time (e.g., one in a regular election and the other simultaneously to fill the seat of a senator who resigned), the one who is sworn in first is senior.