Senate Majority Leaders by BarkerC

This West Virginia Democrat was, at his death in 2010, the longest-serving member of Congress in U.S. history (he was passed by John Dingell in 2013). He remains the longest-serving U.S. Senator in history. (edited at 12:41 pm, February 18, 2016 (PST))

Original question: This West Virginia Republican was, at his death in 2010, the longest serving member of Congress in U.S. history (he was passed by John Dingell in 2013). He remains the longest-serving U.S. Senator in history.