Section 3. The governor and the lieutenant governor must be elected on a joint ballot. Each vote cast for a candidate for governor is deemed cast also for the candidate for lieutenant governor running jointly with the candidate for governor. The joint candidates having the highest number of votes must be declared elected. If two or more joint candidates have an equal and highest number of votes for governor and lieutenant governor, the legislative assembly in joint session at its next regular session shall choose one pair of joint candidates for the offices. The returns of the election for governor and lieutenant governor must be made in the manner prescribed by law.