In case of the death, conviction or impeachment, failure to qualify, resignation, or other disability of the governor, the president of the Senate shall act as governor until the vacancy is filled, or the disability removed; and if the president of the Senate, for any of the above named causes, shall become incapable of performing the duties of governor, the same shall devolve upon the speaker of the House of Delegates; and in all other cases where there is no one to act as governor, one shall be chosen by joint vote of the Legislature. Whenever a vacancy shall occur in the office of governor before the first three years of the term shall have expired, a new election for governor shall take place to fill the vacancy.