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Republican vice presidential candidate, Rep. Paul Ryan, R-Wis., right, is introduced by recording artist Kid Rock at a rally at Oakland University in Rochester, Mich., Monday, Oct. 8, 2012. (AP Photo/Paul Sancya)

Republican vice presidential candidate, Rep. Paul Ryan, R-Wis., right, is introduced by recording artist Kid Rock at a rally at Oakland University in Rochester, Mich., Monday, Oct. 8, 2012. (AP Photo/Paul Sancya)

Celebrity endorsements

Help or hindrance, Hollywood stars have been putting their weight behind politicians for decades.