In Case of the Removal of the President from Office, or of his Death, Resignation, or Inability to discharge the Powers and Duties of the said Office, the Same shall devolve on the Vice President, and the Congress may by Law provide for the Case of Removal, Death, Resignation or Inability, both of the President and Vice President, declaring what Officer shall then act as President, and such Officer shall act accordingly, until the Disability be removed, or a President shall be elected.
Anyone in the line of succession below VP is designated by law, which according to the constitution, only acts as president, not become president.
Edit: But I mean, supreme court could just say that they become president just to make their reign seem more legitimate. We don’t really know anymore. Law is just what the system believes to be law.
Correction: Speaker does not become President, but Acting President. Only VP actually ever takes the title of “President” in succession scenarios.
And there’s disagreement over that.
Article II, Section 1, Clause 6:
Anyone in the line of succession below VP is designated by law, which according to the constitution, only acts as president, not become president.
Edit: But I mean, supreme court could just say that they become president just to make their reign seem more legitimate. We don’t really know anymore. Law is just what the system believes to be law.