For the general municipal election to be held in the year 1985 in every incorporated town with a population of 25,000 or more by the last official census, and every 4 years thereafter, the municipal clerk shall certify the names of the candidates to the proper election authority as provided by the general election law. A president, a clerk, an assessor, a collector, and a supervisor shall be elected for a term of 4 years and until their successors are elected and have qualified. Whenever a vacancy occurs in the office of any of the specified officers, the vacancy shall be filled for the remainder of the term at the next general municipal election in that incorporated town as provided in Section 3.1-10-50. Whenever an election is held for this purpose, the municipal clerk shall certify the office to be filled and the candidates for that office to the election authorities as provided in the general election law. During the period from the time a vacancy occurs until a clerk, assessor, collector, or supervisor is elected and has qualified, the vacancy may be filled by appointment by the president and board of trustees of that incorporated town voting jointly. During the period from the time a vacancy occurs until a president is elected and has qualified, the vacancy may be filled by appointment by the board of trustees of that incorporated town.