Who was the last VP to run for President against his old boss?

THE 2024 PRESIDENTIAL CAMPAIGN FIELD, WHICH already features the first former U.S. President ever to be criminally indicted, is about to get even more unprecedented.

- OLIVIA B. WAXMAN

On June 5, Mike Pence filed paperwork to run for President, making him the first former Vice President to run against the President under whom he served in over 80 years, and only the third ever to do so.

"We haven't had anything like this before," says Joel Goldstein, an expert on the history of American Vice Presidents and law professor emeritus at St. Louis University.

History can be a bit confusing on this point. In the election of 1800, a sitting Vice President, Thomas Jefferson, challenged a sitting President, John Adams, for the top office, but each was the leader of an opposing party. The electoral system was completely different back then; the candidate with the most votes was elected President, and the candidate with the second most votes became Vice President. The 12th Amendment got rid of that system in 1804.