After graduation, he quickly became involved in the local Democratic party and in organized opposition to the Eighteenth Amendment.[1] In 1928 he was named a delegate for Pennsylvania to the Democratic National Convention, supporting Al Smith due to his anti-prohibition platform.[1]
Hemphill served as a Captain in the United States Army during World War I, seeing combat in the Marne, Saint-Mihiel, and the Meuse–Argonne offensive.[1] He was also a lawyer, and a partner at the offices of Hemphill & Brewster, and later Lewis, Wolff, Gourney & Hemphill, during which he legally challenged the 18th amendment and sought its repeal.[1]
Incumbent Republican governor Gifford Pinchot had grown increasingly unpopular near the end of his term due to his strict enforcement of prohibition, anti-worker stances in various strikes across the state including his crackdown of the UMW general strike, as well as his attempts to rewrite the state constitution, coupled with him running afoul of Republican political boss William S. Vare saw a highly competitive campaign.[2]
Hemphill's campaign would be swelled by anti-Pinchot and anti-prohibition Republicans, including William Winston Roper, the famous coach of the Princeton Tigers football team, however, due to his support for working with Republicans more stringent Democrats opposed his campaign, including William B. Wilson, former United States Secretary of Labor.[2][3] Hemphill also saw the support from the Women's Organization for National Prohibition Reform (WONPR), a group concerned that Prohibition had, instead of reducing drunkenness in the country, increased it, and sought to pressure support for the repeal of the Eighteenth Amendment to the United States Constitution.[4]
Hemphill would ultimately be defeated by more than 32,000 votes out of two million cast.[2] However, he carried Philadelphia, a Republican stronghold, and received the endorsement of 47 of the 48 Republican ward leaders there.[1]
Hemphill held a rally in Philadelphia on June 19, 1940, where he endorsed Republican Wendell Willkie for president in the 1940 election before 600,000 Democrats.[5] Hemphill argued that Willkie was more in line with the Democratic platform of 1930 and 1932 than Franklin D. Roosevelt and that the Democratic party had become little more than a rubber stamp for Roosevelt's ambitions.[5]
