Debbie Dingell with Michigan Sen. Carl Levin and then-presidential candidate Barack Obama during a 2008 campaign event in Flint, Mich. Dingell is expected to announce Friday that she will run for her husband's House seat. Alex Brandon/AP hide caption

itoggle caption Alex Brandon/AP

Rep. John Dingell, D-Mich., whose House career stretches nearly 60 years, will retire at the end of his term as the longest-serving member of Congress in history. Manuel Balce Ceneta/AP hide caption

itoggle caption Manuel Balce Ceneta/AP