Pat Roberts

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Former Kansas Sen. Bob Dole speaks during a campaign stop for Republican Sen. Pat Roberts at a mall Monday, Sept. 22, 2014, in Dodge City, Kan. (AP Photo/Charlie Riedel) ** FILE **

Republican Kansas Sen. Pat Roberts talks to supporters at the Johnson County Republican headquarters, Monday, Nov. 3, 2014, in Overland Park, Kan. Incumbent Roberts is locked in a tough contest with independent candidate Greg Orman in Tuesday's midterm election. (AP Photo/Charlie Riedel)

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Kansas Gov. Sam Brownback (left) and Sen. Pat Roberts, both Kansas Republicans, are facing tough re-election bids that analysts say has more to do with candidate troubles than with dissatisfaction with the GOP. (Associated Press)

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Independent U.S. Senate candidate Greg Orman is giving Sen. Pat Roberts, Kansas Republican, a run for his money, but tea party activists say Mr. Orman is "independent" in name only and the Mr. Roberts is the conservative choice. (Associated Press)

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After a tough primary battle, the tea party has thrown it's support behind incumbent Sen. Pat Roberts, Kansas Republican. (Associated Press)

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** FILE ** Senate Rules Committee member Sen. Ted Cruz, R-Texas, right, joined by the committee's ranking member Sen. Pat Roberts, R-Kansas, speaks on Capitol Hill in Washington, Wednesday, April 30, 2014. (AP Photo)