A Civil Service Commission shall be established which shall consist of three (3) electors of the Municipality, not holding other municipal office or appointment, to be appointed by the Mayor, with the concurrence of a majority of Council, for a term of three (3) years; except that of the three (3) to be appointed for a term beginning January 1, 1962, one shall be appointed for a term of one (1) year, one shall be appointed for a term of two (2) years, and one shall be appointed for a term of three (3) years. No more than two (2) members shall be members of the same political party. Any vacancy occurring during the term of any member shall be filled for the unexpired term in the manner authorized for an original appointment.