The Commission shall consist of nine members, three from each county, to be elected by a majority of the legislative delegations of the respective counties, including the Senators. The term for one member from each county shall expire on April 1, 1963, the term for one member from each county shall expire on April 1, 1964, and the term for one member from each county shall expire on April 1, 1965. The successors of the original members shall serve for terms of three years or until their successors have been elected and qualified.