Because the office of the vice president was created almost as an afterthought by the framers of the Constitution, Congress has clarified and defined the role over the years through constitutional amendments.
The original provision for the election of a vice president -- that of runner-up for the presidency -- was soon revealed as flawed. In the 1800 election, Thomas Jefferson and Aaron Burr received the same number of electoral votes. The House of Representatives, charged with voting in the event of an electoral tie, cast their ballots -- and received the same deadlock 35 times. Ultimately, Jefferson won, but the experience was enough for Congress to create the 12th Amendment to the Constitution in 1804, setting up our current system of electors casting different ballots for the president and vice president.
The 25th Amendment was another landmark change in the vice presidency. Prior to 1967, when the amendment was adopted, should the vice president take over as president, resign or die, the office remained vacant until the next election. The 25th Amendment gave the president (whether it is the original president or the newly succeeded former vice president) the power to appoint a new vice president to fill the role. The appointment, like all other presidential appointments, is subject to confirmation by Congress; in this case a majority vote by both the House and the Senate.
The vice presidency was further clarified by the 25th in that it also spelled out the protocol for the transfer of power from the president to the vice president, should the former become incapacitated or unable to carry out the duties of the office. The most straightforward means by which this event can transpire is the president formally alerting the speaker of the House and the Senate president pro tempore that he or she can no longer carry out the responsibilities of the office. The presidency is then transferred to the vice president, who holds the office as acting president until the elected president tells the speaker and president pro tempore that he or she is able to resume the presidency.
A stickier situation arises when the vice president alerts the Senate president and the speaker of the House that the president is unable to carry out the office, essentially grabbing power from the president. However, the Vice President needs the formal support of the majority of the members of the Cabinet for that to transpire. The vice president can also, with a majority of the Cabinet, block a president who's relinquished power from retaking the office. If the president contests this charge of inability, Congress deliberates the issue and can overturn the vice president's role as acting president with a two-thirds vote by both the House and the Senate.
This power grab has never taken place in the history of the United States, and only once has a president transferred power to a vice president since the 25th Amendment was adopted. Prior to undergoing cancer surgery, President Ronald Reagan transferred power to Vice President George H.W. Bush, though it was technically an informal transfer since Reagan didn't invoke the 25th Amendment.
The Constitution lays out the qualifications for vice president, and they're the same as those required for the president. The vice president must have been born in the United States (or on U.S. soil abroad), must be at least 35 years old and must have spent at least 14 years of his or her life in the United States.
Throughout the history of the vice presidency, those who've held the office have helped mold and shape it. Read about the evolution of the U.S. vice presidency on the next page.