U.S. Rep. Paul Ryan, R-Wis., right, hears from a constituent during a "listening session" Tuesday at Gateway Technical College in Kenosha, Wis. Ryan's plan to fundamentally restructure Medicare and cut social safety net programs has proved to be a tough sell to many Republican voters the last few weeks. Jeffrey Phelps/AP hide caption

Defense Secretary Robert Gates talks with troops during a visit April 7 at Camp Victory in Baghdad. Chip Somodevilla/Getty Images hide caption

Soldiers care for the wounded on the first day of the Battle of Passchendaele on July 31, 1917. Fought in West Flanders, Belgium, Passchendaele was one of the war's most costly clashes. Imperial War Museum, London hide caption

Ambrose Akinmusire. Courtesy of the artist. hide caption