Reading a book that happened to deal with Theodore Roosevelt, I was intrigued to learn something I hadn't known before about his campaign for and election as Vice President in 1900.
It's well-known that he'd been eased into this position by Thomas Platt, the Republican party boss of New York state, who'd wanted to kick TR upstairs from Governor into what he considered a harmless position. Of course, this backfired on Platt when President McKinley was assassinated and TR inherited the position of President. One question is why, both on such grounds and simply for security, did officials tend to ignore the possibility of assassination? It was in the air. McKinley's assassin was inspired by the assassination of the King of Italy the year before. Two US Presidents had been assassinated within the previous 40 years.
But what I'm dealing with here is the prospect of being Vice President for four years. TR was an active man; it would have been a stultifying job for him. Indeed, although he was riding a crest of popularity from his (overblown) exploits in the Spanish war of 1898, he knew he could be entirely forgotten by the time his term was over, and he took steps to get tutored in the law so that he could earn his living that way after leaving office. (Private tutoring was still a common avenue for legal training then.)
However, TR's initial receptivity to being run for VP was the idea that he could use it to position himself to run for President in 1904 when McKinley's second term as President ran out. That's what was new information to me. And what I wondered was, was this feasible? No incumbent VP had been elected President since Martin Van Buren in 1836, and he - not incidentally - had been the last VP up to that time, or for a considerable time thereafter, who was the President's right-hand man and not a ticket-balancer.
But when I looked it up, I found that the idea of a VP running for President when the incumbent stepped down was not unknown post-Van Buren. It's easy to forget that one other such VP had run a full campaign, and that was John C. Breckinridge for the Southern Democrats when the party split in 1860. I found on checking that two other such VPs had attempted presidential runs, George M. Dallas in 1848 and Adlai Stevenson (the elder) in 1896. They didn't get very far with them, and Breckinridge didn't win either, but the idea was in the air. And it remained so, as several other VPs in upcoming years attempted presidential runs (Fairbanks 1908, Marshall 1920, Garner 1940, Barkley 1952) before Richard Nixon finally achieved nomination, and near-election, in 1960. Since then three more VPs have been presidential nominees, of whom one won election, and two more ex-VPs have run in subsequent elections, of whom one won and he's in office right now.