Rubio: Aggressive, with large followings, appears to make personal use of Twitter more than staff-generated Facebook. Takes lots of shots at the health law. On Facebook, lists "Pulp Fiction" movie and "The Tudors" historical fiction TV series among favorites.
Ryan: King of Facebook among potential rivals in both parties, with nearly 4.9 million likes. Seeks $10 donations for "Team Ryan" bumper stickers for his PAC and kisses a fish. Posts photo of Obama with his feet up on Oval Office desk. Commanding presence on Twitter, too, via an account associated with his PAC and another as congressman.
Santorum: Active on Twitter and Facebook.
Walker: Posts vigorously on Facebook and on his Twitter accounts. Many exclamation points. "Glad USDA is keeping cranberries on school menus. I drink several bottles of cranberry juice each day!" And, "Green Bay Packers signing Julius Peppers to a 3-year deal is HUGE!" Promotes policy achievements and his TV appearances, reflects on sports, pokes Obama.
Associated Press writers Ken Thomas, Josh Lederman and Nancy Benac in Washington; Brian Witte in Annapolis, Maryland; Tom Beaumont in Des Moines, Iowa; Steve Peoples in Boston; Michael Virtanen in Albany, New York; Will Weissert in Austin, Texas; and Melinda Deslatte in Baton Rouge, Louisiana, contributed to this report.