The original Adlai E. Stevenson was a successful attorney and politician in Illinois, but unlike Lincoln and other Republicans, Stevenson was a lifelong a Democrat. During the first Cleveland administration, he served as an assistant postmaster general, knocking many thousands of Republicans off the payroll in favor of Democrats.
Party loyalty brought him the vice presidency during Cleveland's second administration, and almost the presidency itself, when the president underwent risky surgery to remove a tumor from his jaw on July 1, 1893, though Cleveland kept the treatment so secret that there's no indication that Stevenson knew.
The former vice president ran for the office again in 1900, on the ticket with William Jennings Bryan, but a Democratic loss was a forgone conclusion that year. Stevenson died in 1914.