Between 1789 and 1967 eight presidents died in office. In 1841, the death of the first president to die in office, William Henry Harrison (a short but tragic tale for another time) raised the question of succession in the event of the executive’s demise. Amidst the confusion, Harrison’s vice president, John Tyler, had to insist that the president’s death meant that he became president, not just “acting president.”
Still, it took the country another one hundred and twenty-six years to formally add an amendment to the constitution outlining the path of succession, and what to do if the president became unable to perform his duties.
It wasn’t as if the question wasn’t raised again–in the time after Harrison’s death until the adoption of the amendment in 1967, four presidents were assassinated, three died in office, and others suffered medical conditions that rendered them incapable to serve. Without clear guidelines, Woodrow Wilson’s stroke made his wife the most powerful woman in America. President Eisenhower, his VP Nixon, and the Attorney General at the time, Herbert Brownell Jr., tried to clarify the procedure after Ike’s heart attack–Nixon would preside over Cabinet meetings when Eisenhower was indisposed, but never assumed power.
The issue became more urgent after Kennedy’s assassination in 1963. Given that his death had elevated Lyndon Johnson to the presidency (a man who had a history of heart problems) there was a pressing need to spell out what should happen if LBJ died or became unable to preside as president.
What does the 25th amendment do? Several things.
First, it reaffirms John Tyler’s actions: if the president dies, resigns, or is removed from office, power is transferred to the vice president.
Second, it allows the president to nominate a vice president if the original VP leaves office for whatever reason (this was an issue in 1868 during Andrew Johnson’s impeachment hearing, since he had no vice president. At the time, it was customary to wait for the next election if a VP left office. It was invoked for the first time in 1973, when Spiro Agnew resigned as Nixon’s VP. Nixon nominated Gerald Ford to replace him).
Third, the president can send an official notice to Congress saying he is unable to perform his duties, and another note when he is ready to resume (as in the case of a medical procedure–George W. Bush invoked this section in 2002). In the interim, the vice president has the powers of the president.
Fourth, if the vice president and a majority of the Cabinet or Congress believe that the president is unable to perform his duties, they can remove him from power. This is the only section that has never been invoked.