Among outside groups — that is, not candidates or party committees — more than half of this cycle's political ads are financed by secret donors. iStockphoto hide caption

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Scott Hildebrand, a Democrat, and Mike Jansen, a Republican, are competing to be the new sheriff in Campbell County, Ky., but they're also abiding by an agreement to keep their race clean. Images courtesy of the candidates hide caption

itoggle caption Images courtesy of the candidates

Senate Majority Leader Harry Reid, D-Nev., speaks to reporters after a Democratic caucus meeting at the Capitol last Tuesday. J. Scott Applewhite/AP hide caption

itoggle caption J. Scott Applewhite/AP

Immigrants from Honduras and El Salvador who crossed the U.S.-Mexico border illegally are stopped in Granjeno, Texas, on June 25. President Obama asked Congress this week for $3.7 billion to cope with thousands of minors from Central America who are illegally crossing the U.S. border. Eric Gay/AP hide caption

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Detainees sleep in a holding cell at a U.S. Customs and Border Protection processing facility in Brownsville, Texas, on June 18. The White House on Tuesday sought $3.7 billion to deal with the immigration crisis at the border. Eric Gay/AP hide caption

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Vice President Biden (from left), Health and Human Services Secretary Kathleen Sebelius, President Obama and Budget Director Sylvia Mathews Burwell at the White House Friday. Sebelius is stepping down. Burwell is being nominated to replace her. Charles Dharapak/AP hide caption

itoggle caption Charles Dharapak/AP

Former Secretary of State Hillary Clinton ducks after a woman threw a shoe at her while she was delivering remarks at the Institute of Scrap Recycling Industries conference on Thursday in Las Vegas. Isaac Brekken/Getty Images hide caption

itoggle caption Isaac Brekken/Getty Images

Former President George W. Bush says his favorite from among the portraits he's painted of world leaders is the one he did of his father, former President George H.W. Bush. "I painted a gentle soul," he says. George W. Bush Presidential Center hide caption

itoggle caption George W. Bush Presidential Center

Rep. Mike Rogers, R-Mich., during an appearance last year on CBS News' Face the Nation. The chairman of the House Intelligence Committee says he won't seek re-election in November. Chris Usher/AP hide caption

itoggle caption Chris Usher/AP

Former Secretary of Defense James Schlesinger speaks at the Council on Foreign Relations in New York in December, 2006. Brendan McDermid/Reuters/Landov hide caption

itoggle caption Brendan McDermid/Reuters/Landov