C.R.S. § 2-2-504

(1) Nothing in this part 5 or in any redistricting plan removes any senator from his or her office for the term for which the senator was elected, and each such senator shall serve the term for which he or she was elected. (2) If any senator elected at a general election in a year ending in 0 vacates his or her seat prior to the convening of the regular legislative session in the next year ending in 3, such vacancy must be filled from the district from which the senator was elected in accordance with section 1-12-203 . If such vacancy occurs more than fifty-five days before the general election in the next year ending in 2, there must be an election at the general election in that year ending in 2 for the remainder of such senator’s term from the senatorial district created by the legislative commission. Nomination of candidates at such election must be in accordance with article 4 of title 1 . (3) If any senator elected at a general election in a year ending in 0 vacates his or her seat on or after the convening of the regular legislative session in the next year ending in 3, such vacancy must be filled from the senatorial district created by the legislative commission in accordance with section 1-12-203 .