Two of such commissioners at least shall always be selected from the 2 leading political parties of the state, one from each of such parties, and all shall be legal voters residing in such city, village or incorporated town, and be persons of well known political convictions and of approved integrity and capacity. No commissioner can hold any other political office. Whenever it shall come to the knowledge of the court that one of the leading political parties of the state is not represented upon such commission by a person of the same political faith, the court shall at once remove one of such commissioners and fill the vacancy with a member of the leading political party not so represented.