What historical or constitutional precedents exist for presidents serving as vice president afterward?

1. The historical record: presidents who were once vice presidents, not vice presidents who were once presidents

Across centuries of U.S. history the standard pattern documented in authoritative lists is that vice presidents sometimes ascend to the presidency—either by election or by succession after a president’s death or resignation—but the record does not contain an example of a former president later accepting the vice-presidency; sources list 15 vice presidents who went on to become president and catalogue many pathways from VP to president, including election and succession, but offer no instance of the reverse career arc ^{[1] [3] [6]}.

2. How common is the VP→President path, and why that matters to the question

The dataset makes clear that VP-to-president remains relatively uncommon: roughly 15 of the nearly fifty men who served as vice president ultimately became president, and of those, a substantial fraction became president by succeeding a deceased or resigned president rather than by later election—facts underscoring that the historical mobility runs primarily in one direction, from vice president up, not from president down to vice president ^{[3] [6]}.

3. Constitutional mechanics that touch on the issue (what the sources cover)

The supplied sources explain several constitutional arrangements relevant to the vice presidency—how the Twelfth Amendment revised electoral mechanics after 1800, and how the Twenty-Fifth Amendment created procedures for filling a vacant vice-presidency and for temporary presidential disability—showing the Constitution provides mechanisms for succession and appointment but, in the material provided, does not discuss a mechanism for a former president to become vice president specifically nor cite any prohibition against it ^{[4] [5] [7]}.

4. Notable anomalies and one-of-a-kind careers that clarify the limits of precedent

The historical literature highlights unusual cases that define the edges of precedent—Gerald R. Ford, for example, was appointed vice president under the 25th Amendment and later became president without having been elected to either office, an idiosyncrasy that underscores procedural flexibility but still sits inside the conventional VP→P trajectory rather than the reverse ^{[8] [3]}. Sources also note vice presidents who served under more than one president (George Clinton, John C. Calhoun), but these instances do not demonstrate a president later serving as vice president ^{[1] [2]}.

5. Interpretation, alternative viewpoints, and limits of the reporting

The absence of any historical example in the provided lists establishes a strong empirical point: there is no historical precedent for a president later serving as vice president in U.S. history as documented by Senate and historical compilations ^{[1] [3] [2]}. That said, the supplied reporting does not include a focused constitutional-law analysis explicitly answering whether the Constitution would forbid a former president from becoming vice president; it documents succession rules and historical cases but stops short of a definitive legal opinion on hypothetical eligibility or on modern political feasibility ^{[4] [5]}. Political scientists and constitutional scholars—sources not included here—would typically weigh factors like the Twelfth Amendment’s electoral design, the Twenty-Second Amendment’s presidential term limits, and partisan politics when assessing plausibility; those deeper analyses are beyond what these sources provide.