Orrin Grant Hatch (born March 22, 1934) is an American politician who is the President pro tempore of the United States Senate, serving since January 2015. A member of the Republican Party, he serves as the senior United States Senator for Utah. In office since 1977, Hatch is the most-senior Republican Senator.Hatch has served as either the chairman or ranking minority member of the Senate Judiciary Committee from 1993 to 2005.