Former Sen. Rick Santorum, R-Pa., who was lagging in the polls in 2012 but ended up winning in Iowa, says debate criteria this time are too exclusive. Jae C. Hong/Associated Press hide caption

itoggle caption Jae C. Hong/Associated Press

Hillary Clinton delivers the keynote address at the 18th annual David N. Dinkins Leadership and Public Policy Forum at Columbia University in New York on April 29. Trevor Collens/AFP/Getty Images hide caption

itoggle caption Trevor Collens/AFP/Getty Images

Republican presidential candidate Sen. Rand Paul's 10 1/2 hours on the Senate floor were about liberty, the Constitution and the need to stand out in a field of presidential hopefuls. Andrew Harnik/AP hide caption

itoggle caption Andrew Harnik/AP

Doug Hughes said he sees his future as working for "the cause of getting a Congress — not more liberal, not more conservative — but a Congress that is working for the people." Peter Overby/NPR hide caption

itoggle caption Peter Overby/NPR

President Obama tells The Atlantic that the loss of Ramadi to the self-declared Islamic State is a "setback," but he denies the U.S. is losing to the group. Kathy Willens/AP hide caption

itoggle caption Kathy Willens/AP

In an image from Senate video, presidential candidate Sen. Rand Paul speaks on the floor of the U.S. Senate Wednesday afternoon at the start of an almost 11-hour speech opposing renewal of the Patriot Act. AP hide caption

itoggle caption AP