W. Va. Code § 3-10-4
(a)
(b) If there is a vacancy in the representation from this state in the Senate of the United States Congress, the vacancy shall be filled by the Governor of the state by appointment. The Governor shall make the appointment from a list of three legally qualified persons submitted by the party executive committee of the same political party with which the person holding the office immediately preceding the vacancy was affiliated at the time of the previous election for that office. The list of qualified persons to fill the vacancy shall be submitted to the Governor within 15 days after the vacancy occurs, and the Governor shall duly make his or her appointment to fill the vacancy from the list of legally qualified persons within five days after the list is received. If the list is not submitted to the Governor within the 15-day period, the Governor shall appoint, within five days thereafter, a legally qualified person of the same political party with which the person holding the office immediately preceding the vacancy was affiliated at the time of the previous election for that office: Provided, That any such person appointed by the Governor must have been affiliated with that political party for at least one year prior to the occurrence of the vacancy.
Furthermore,
(2) If the vacancy occurs after the primary cutoff date, but on or before the general cutoff date, then the Governor shall issue a proclamation providing for: