William Howard Taft (September 15, 1857 – March 8, 1930) was the 27th president of the United States (1909–1913) and the tenth chief justice of the United States (1921–1930), the only person to have held both offices. Taft was elected president in 1908, the chosen successor of Theodore Roosevelt, but was defeated for re-election by Woodrow Wilson in 1912 after Roosevelt split the Republican vote by running as a third-party candidate. In 1921, President Warren G. Harding appointed Taft to be chief justice, a position in which he served until a month before his death.
The first photographic image on pins dates to 1860. Abraham Lincoln and his various opponents used the tintype or ferrotype photo process. The first mass production of metal political buttons date back to the 1896 William McKinley campaign for president with "celluloid" buttons with one side of a metal disk covered with paper (printed with the message) and protected by a layer of clear plastic.
Since 1916, buttons have also been produced by lithographing the image directly onto the metal disk. A celluloid-type button is fastened to a garment using a pin on the back side of the button (in recently produced buttons, the pin generally fits into a safety-pin-style catch). A lithographed button may fasten with a pinback or with a metal tab which folds over a lapel or pocket.
One of the most famous uses of campaign buttons occurred during the 1940 U.S. presidential election, when Wendell Willkie's campaign produced millions of lithographed slogan buttons in rapid response to news items about President Franklin D. Roosevelt.
Time has a great feature on Campaign buttons, click here