United States Senate

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Former Massachusetts Senator Scott Brown acknowledges his wife Gail as he announces his plans to form an exploratory committee to enter New Hampshire's U.S. Senate race against Democratic Sen. Jeanne Shaheen,, Friday, March 14, 2014 in Nashua, N.H. (AP Photo/Jim Cole)

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Republican U.S. Senate candidate Richard Cash, center, signs an agreement to support any challenger who gets into a runoff with U.S. Sen. Lindsey Graham in June as he stands on the steps of the Statehouse, Thursday, March 13, 2014, in Columbia, S.C. Six GOP candidates have said they want to take on Graham as he seeks a third term. (AP Photo/Jeffrey Collins)

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Republican U.S. Senate candidate Dave Feliciano speaks after signing an agreement to support any challenger who gets into a runoff with U.S. Sen. Lindsey Graham in June, on the steps of the Statehouse Thursday, March 13, 2014, in Columbia, S.C. Six GOP candidates have said they want to take on Graham as he seeks a third term. (AP Photo/Jeffrey Collins)

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Republican U.S. Senate candidate Bill Connor speaks after signing an agreement to support any challenger who gets into a runoff with U.S. Sen. Lindsey Graham in June, on the steps of the Statehouse, Thursday, March 13, 2014, in Columbia, S.C. Six GOP candidates have said they want to take on Graham as he seeks a third term. (AP Photo/Jeffrey Collins)

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Republican U.S. Senate candidate Richard Cash speaks after signing an agreement to support any challenger who gets into a runoff with U.S. Sen. Lindsey Graham in June, on the steps of the Statehouse, Thursday, March 13, 2014, in Columbia, S.C. Six GOP candidates have said they want to take on Graham as he seeks a third term. (AP Photo/Jeffrey Collins)

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Republican U.S. Senate candidate Lee Bright speaks after signing an agreement to support any challenger who gets into a runoff with U.S. Sen. Lindsey Graham in June, on the steps of the Statehouse, Thursday, March 13, 2014, in Columbia, S.C. Six GOP candidates have said they want to take on Graham as he seeks a third term. (AP Photo/Jeffrey Collins)