(a) When the governor is physically absent from the Commonwealth, the lieutenant governor shall be acting governor. If the lieutenant governor is also absent or is otherwise unavailable, the presiding officer of the senate shall be acting governor.
(b) When the governor is unable to discharge the duties of the office by reason of physical or mental disability, the lieutenant governor shall be acting governor. If the lieutenant governor is unavailable, the presiding officer of the senate shall be acting governor. If the person next in succession to the governor has reason to believe that the governor is unable to discharge the duties of the office, that person shall file a petition to declare a vacancy with the Commonwealth appeals court or the United States District Court if no Commonwealth appeals court has been created under article IV, section 3. The court has original and exclusive jurisdiction to determine all questions regarding the disability of the governor and the existence of a vacancy in the office of governor.