Sheldon Adelson listens as New Jersey Gov. Chris Christie speaks during the Republican Jewish Coalition meeting on March 29 in Las Vegas. Several possible GOP presidential candidates gathered in Las Vegas as Adelson, a billionaire casino magnate, looks for a new favorite to help on the 2016 race for the White House. Julie Jacobson/AP hide caption

itoggle caption Julie Jacobson/AP

Sen. Mary Landrieu, D-La., speaks at an Oct. 2013 news conference on Capitol Hill in Washington. Landrieu's support for the Affordable Care Act is center stage in her campaign for a fourth Senate term. Evan Vucci/AP hide caption

itoggle caption Evan Vucci/AP

President Obama speaks in the James Brady Press Briefing Room of the White House in November 2013, shortly after the Senate voted 52-48 to weaken the power of the filibuster. Evan Vucci/AP hide caption

itoggle caption Evan Vucci/AP

Levees, like this one in New Orleans, must be certified by the U.S. Army Corps of Engineers before appearing on federal flood maps. This change has resulted in higher flood insurance premiums in some areas. Mario Tama/Getty Images hide caption

itoggle caption Mario Tama/Getty Images