The original wording of the Constitution on who should succeed a president unable to complete his term was vague enough to spur controversy in 1841. Reprinted below is an excerpt from Article II of the Constitution that describes what should happen if a president is unable to complete his term.

In 1967, the Constitution was amended to clarify the line of succession should a president be unable to complete his term. An excerpt from that amendment follows the passage taken from Article II. The term "pro tempore" that appears in the amendment, refers to the "temporary" leader of the Senate—the Senator (usually from the majority party) who runs day-today operations in that legislative body.

From Article II of the Constitution: