Tennessee Constitution Art. II, § 15

(a) When twelve months or more remain prior to the next general election for legislators, a successor shall be elected by the qualified voters of the district represented, and such successor shall serve the remainder of the original term. The election shall be held within such time as provided by law. The legislative body of the replaced legislator's county of residence at the time of his or her election may elect an interim successor to serve until the election.

(b) When less than twelve months remain prior to the next general election for legislators, a successor shall be elected by the legislative body of the replaced legislator's county of residence at the time of his or her election. The term of any Senator so elected shall expire at the next general election for legislators, at which election a successor shall be elected.

(c) Only a qualified voter of the district represented shall be eligible to succeed to the vacant seat.