Full Text of the 12th Amendment
The Electors shall meet in their respective states and vote by ballot for President and Vice-President, one of whom, at least, shall not be an inhabitant of the same state with themselves; they shall name in their ballots the person voted for as President, and in distinct ballots the person voted for as Vice-President, and they shall make distinct lists of all persons voted for as President, and of all persons voted for as Vice-President, and of the number of votes for each, which lists they shall sign and certify, and transmit sealed to the seat of the government of the United States, directed to the President of the Senate;—The President of the Senate shall, in the presence of the Senate and House of Representatives, open all the certificates and the votes shall then be counted;—The person having the greatest Number of votes for President, shall be the President, if such number be a majority of the whole number of Electors appointed; and if no person have such majority, then from the persons having the highest numbers not exceeding three on the list of those voted for as President, the House of Representatives shall choose immediately, by ballot, the President. But in choosing the President, the votes shall be taken by states, the representation from each state having one vote; a quorum for this purpose shall consist of a member or members from two-thirds of the states, and a majority of all the states shall be necessary to a choice. And if the House of Representatives shall not choose a President whenever the right of choice shall devolve upon them, before the fourth day of March next following, then the Vice-President shall act as President, as in the case of the death or other constitutional disability of the President—The person having the greatest number of votes as Vice-President, shall be the Vice-President, if such number be a majority of the whole number of Electors appointed, and if no person have a majority, then from the two highest numbers on the list, the Senate shall choose the Vice-President; a quorum for the purpose shall consist of two-thirds of the whole number of Senators, and a majority of the whole number shall be necessary to a choice. But no person constitutionally ineligible to the office of President shall be eligible to that of Vice-President of the United States.
Note: Words in italics indicate provisions that were later dropped from the Constitution.
After the disputed election of 1800, this amendment required separate designation of presidential and vice presidential candidates, each of whom must meet the same qualifications for eligibility as the president. Source: U.S. Senate
Approved by Congress on December 9, 1803, and ratified by the states on June 15, 1804, the Twelfth Amendment modifies the way the Electoral College chooses the presidentand vice president. Article II, Section 1 of the Constitution, which established the Electoral College, provided that each state appoint electors equal to the total number of House and Senate members in their state and that the electors shall vote for two persons.
The presidential candidate who received the most electoral votes won the presidency; the runner-up became the vice president. In 1796, this meant that the president and the vice president were from different parties and had different political views, making governance more difficult. The adoption of Amendment XII solved this problem by allowing each party to nominate their team for president and vice president.
The inhabitant clause of the Twelfth Amendment also suggests strongly that the president and vice president should not be from the same state. Although the provision does not directly disqualify a vice president who is from the same state as the president, the provision disqualifies the electors from that state from voting for both offices.
Prior to the 2000 election, both presidential candidate George W. Bush and vice presidential candidate Dick Cheney lived in and voted in Texas. To avoid problems with the inhabitant clause, Cheney registered to vote in Wyoming, where he previously lived.
The Twelfth Amendment also specifies how the president and vice president are to be selected should neither candidate obtain the votes of a majority of the electors: the House of Representatives selects the new president from the top three candidates. This is a slight variation from the original provision, which allowed the choice from among the top five candidates. However, the vote within the House is by state, not by representative. This gives equal weight to all states—the smaller, less populated states as well as the larger, more populated ones—and makes it more likely that the ultimate winner may not be the candidate who obtains the majority of the popular vote.
Lastly, this amendment extends the eligibility requirements to become president (the candidate must be a natural born citizen, must be at least thirty-five years old, and must have been a resident of the United States for fourteen years) to the vice president since no person who is constitutionally ineligible to be president can be vice president. Source: Annenberg Classroom