"Section 1. In case of the removal of the President from office or of his death or resignation, the Vice President shall become President.
Section 2. Whenever there is a vacancy in the office of the Vice President, the President shall nominate a Vice President who shall take office upon confirmation by a majority vote of both Houses of Congress.
Section 3. Whenever the President transmits to the President Pro Tempore of the Senate and the Speaker of the House of Representatives is written declaration that he is unable to discharge the powers and duties of his office, and until he transmits to them a written declaration to the contrary, such powers and duties shall be discharged by the Vice President as Acting President. Section 4. Whenever the Vice President and a majority of either the principal officers of the executive departments or of such other body as Congress may by law provide, transmit to the President pro tempore of the Senate and the Speaker of the House of Representatives their written declaration that the President is unable to discharge the powers and duties of his office, the Vice President shall immediately assume the powers and duties of the office as Acting President.
Thereafter, when the President transmits to the President pro tempore of the Senate and the Speaker of the House of Representatives his written declaration that no inability exists, he shall resume the powers and duties of his office unless the Vice President and a majority of either the principal officers of the executive department or of such other body as Congress may by law provide, transmit within four days to the President pro tempore of the Senate and the Speaker of the House of Representatives their written declaration that the President is unable to discharge the powers and duties of his office. Thereupon Congress shall decide the issue, assembling within forty-eight hours for that purpose if not in session. If the Congress, within twenty-one days after receipt of the latter written declaration, or, if Congress is not in session, within twenty-one days after Congress is required to assemble, determines by two-thirds vote of both Houses that the President is unable to discharge the powers and duties of his office, the Vice President shall continue to discharge the same as Acting President; otherwise, the President shall resume the powers and duties of his office."
- 25th Amendment of the United States Constitution
The 25th Amendment outlines the procedures that must be taken place when the President is unable to complete his term. The Vice President fills this vacancy and serves as the President.
My first media segment is actually a proposal: One Heartbeat Away by Birch Bayh
In 1963, Senator Kenneth Keating of New York proposed a Constitutional amendment which would have enabled the Congress to enact legislation providing for how to determine when a President is disabled, rather than, as the Twenty-fifth amendment does, having the Constitution so provide. This is a very important section of the amendment.