Government Code §74.091

(a) There is a local administrative district judge in each county. (b) In a county with two or more district courts the judges of those courts shall elect a district judge as local administrative district judge: (1) for a term of two years; or (2) if the district judge's term ends before the second anniversary of the date the district judge is elected as local administrative judge, for the remainder of the district judge's term. (b-1) The local administrative district judge may not be elected on the basis of rotation or seniority. (c) In a county with only one district judge, the district judge serves as the local administrative district judge.