“These are two intensely competitive men who made a judgment early in their careers that their path to success is going to be willing themselves into the positions they wanted,” said Evan Osnos, the author of a just-completed biography of Mr. Biden. “That did not leave much room for getting drunk.”

It has been nearly a century since temperance had much bearing on American politics. The Prohibition Era began 101 years ago with ratification of the 18th Amendment to the Constitution and ended in 1933 with its repeal.

“There was a time in American public life when character was associated with a level of sobriety,” said Tim Naftali, a presidential historian. “I think that disappeared with the end of Prohibition.”