With the Republican nomination mostly wrapped up, and the Democratic race down to two, it’s not too early to start thinking about vice presidential running mates. It’s one of the sad songs in American history.
In the nineteenth century, three vice presidents succeeded to the presidency, and all were disasters. Worse yet, all adopted policies inconsistent with those of the man the succeeded:
John Tyler —

A Virginia Democrat selected to broaden the electoral appeal of the largely-unknown William Henry Harrison, a Whig, Tyler served all but 40 days of Harrison’s term. Tyler, often referred to as His Accidency, had a terrible time with Congress, where impeachment resolutions were prepared but never pursued.
Millard Fillmore —

A New Yorker, Fillmore served more than half of Zachary Taylor’s term. Though a Virginian, Taylor opposed the extension of slavery into Western territories, a position that Fillmore repudiated when he took over in the Executive Mansion. A distinct step backward. Fillmore was the Know-Nothing Party candidate for president in 1856, a nativist, anti-immigration party.
Andrew Johnson — As the only Southern congressman or senator who did not resign with the secession of the Southern states, Johnson of Tennessee was added to Lincoln’s ticket in 1864, replacing Hannibal Hamlin of Maine. Serving all but five weeks of Lincoln’s term, Johnson was a disaster, benignly supporting the restoration of largely Confederate state governments that repressed the freed slaves in a brutal fashion. The story of his impeachment trial — which fell one vote short of conviction — is the subject of the book I’m working on now.
Each man was selected for vice president for short-term political reasons, but proved to be a long-term political liability. Next time . . . the Twentieth Century Veeps.