Final answer:
Prior to the passage of the Twelfth Amendment, both the President and Vice President were not elected by the people. With the ratification of the 25th Amendment in 1967, a vacancy in the Vice Presidency may be filled by the President, who appoints a Vice President subject to majority votes in both the House and the Senate.
Step-by-step explanation:
Prior to the passage of the Twelfth Amendment, both the President and Vice President were not elected by the people. The electoral college initially selected two candidates - one for President, and the runner up for Vice President. With the ratification of the 25th Amendment in 1967, a vacancy in the Vice Presidency may be filled by the President, who appoints a Vice President subject to majority votes in both the House and the Senate.