After a record-setting 59 years, six rounds of redistricting, and 876 C-SPAN appearances, House Dean and Michigan Democratic Rep. John Dingell announced his retirement this morning. And while the move means fellow Rep. John Conyers (MI-13) is next in line to become the longest-serving member of the House, Dingell's MI-12 remains a Solid Democratic seat.

For years, there has been widespread expectation that Dingell's wife, Democratic National Committeewoman and former General Motors executive Debbie Dingell, will run for her husband's seat. Michigan's 12th CD includes Dearborn and most of the "Downriver" locales that have made up the Dingell family's base, and President Obama took 66 percent here in 2012.

However, the liberal college town of Ann Arbor was added to the 12th CD in the post-2000 round of redistricting, and the only question is whether an Ann Arbor-style "progressive" candidate such as state Sen. Rebekah Warren enters the race. Even if she does, Dingell would be considered the favorite, considering only about a quarter of the 12th CD's primary votes come from Ann Arbor.

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