Mark Begich of Alaska, Max Baucus of Montana, Kay Hagan of North Carolina, Tim Johnson of South Dakota, Mary Landrieu of Louisiana and Mark Pryor of Arkansas.
Sen. Frank Lautenberg of New Jersey is an obvious candidate to retire. He'll be 90 by November 2014. And Jay Rockefeller of West Virginia will be 77 by the midterms.
I think dems lose all 8 of these seats, and defend most, if not all of the other 12.