Former Maryland Gov. Martin O'Malley, a Democrat who is considering a 2016 presidential campaign, is interviewed by NPR's Steve Inskeep. Ariel Zambelich/NPR hide caption

itoggle caption Ariel Zambelich/NPR

Reporters and campaign staffers rush to their cars to get to Hillary Clinton's first Iowa campaign stop. Tamara Keith/NPR hide caption

itoggle caption Tamara Keith/NPR

Hill staffers and PGA professionals mingle Wednesday at this year's National Golf Day event on Capitol Hill, which included an annual Democrats versus Republicans putting challenge. Emily Jan/NPR hide caption

itoggle caption Emily Jan/NPR

"We need to fix our dysfunctional political system and get unaccounted money out of it, once and for all, even if that takes a constitutional amendment," Hillary Clinton said at Kirkwood Community College in Iowa Tuesday. Michael B. Thomas/AFP/Getty Images hide caption

itoggle caption Michael B. Thomas/AFP/Getty Images

The Alfred P. Murrah Federal Building was "literally right up against the road so it was extremely vulnerable," said architect Barbara Nadel. One of the government's first responses was to close a two-block stretch of Pennsylvania Avenue in front of the White House. AFP/AFP/Getty Images hide caption

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It's been 35 years since Ronald Reagan announced his run for president. He did so just two months before the Iowa caucuses, unlike the protracted campaigning that takes place today. WJZ/AP hide caption

itoggle caption WJZ/AP