Twentieth Amendment, Section 4:

The Congress may by law provide for the case of the death of any of the persons from whom the House of Representatives may choose a President whenever the right of choice shall have devolved upon them, and for the case of the death of any of the persons from whom the Senate may choose a Vice President whenever the right of choice shall have devolved upon them.

In 1947, Congress adopted the Presidential Succession Act,1 which provided for the Speaker of the House to “act as President” 2 followed by the President Pro Tempore of the Senate, and then by the department heads in the order in which each department had been established.

Footnotes

1

Presidential Succession Act of 1947, Pub. L. No. 80-199, 61 Stat. 380 (codified as amended at 3 U.S.C. § 19).

2

Id. § 19(1).