Bank of America stadium in Charlotte, N.C., where President Obama will accept his party's nomination on Sept. 6. Jeff Siner/MCT/Landov hide caption

itoggle caption Jeff Siner/MCT/Landov

Daniella Urbina, a field organizer for President Obama in Denver, appears in a Spanish-language campaign ad. YouTube hide caption

itoggle caption YouTube

Democrat Ron Barber (left) and Republican Jesse Kelly during a May 23 debate in Tucson. They are running Tuesday in a special election to replace retired Rep. Gabrielle Giffords. Kelly Presnell/Arizona Daily Star hide caption

itoggle caption Kelly Presnell/Arizona Daily Star

Democratic Senate candidate Heidi Heitkamp greets a supporter before a town hall meeting in Minot, N.D., on May 3. Dale Wetzel/AP hide caption

itoggle caption Dale Wetzel/AP

An air traffic controller works at the Atlanta TRACON, or terminal radar approach control, facility in Peachtree City, Ga. The FAA's NextGen program will modernize the air traffic control system, transforming it from radar to GPS-based technology. David Goldman/AP hide caption

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Joe Ricketts, whose American Film Company produced The Conspirator, arrives at the film's premiere during the Toronto International Film Festival in 2010. Alberto E. Rodriguez/Getty Images hide caption

itoggle caption Alberto E. Rodriguez/Getty Images

Nebraska state Sen. Deb Fischer applauds supporters at her election party Tuesday in Lincoln, Neb. At right is Fischer's mother, Florence Strobel. Nati Harnik/AP hide caption

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The four top Republicans seeking the GOP nomination for the U.S. Senate in Nebraska — state Sen. Deb Fischer (from left), state Attorney General Jon Bruning, state Treasurer Don Stenberg and investment adviser Pat Flynn — recite the Pledge of Allegiance before a debate in Omaha last month. Nati Harnik/AP hide caption

itoggle caption Nati Harnik/AP

An image from the Republican National Committee's Facebook page advertises its new "Social Victory Center" app. RNC via Facebook.com hide caption

itoggle caption RNC via Facebook.com

House Speaker John Boehner administers the House oath to Rep. Jason Altmire, D-Pa., on Jan. 5, 2011. Alex Brandon/AP hide caption

itoggle caption Alex Brandon/AP

In a campaign video, the Mitt Romney campaign accuses President Obama of "spending millions to sling mud — or oil — at Mitt Romney." MittRomney.com hide caption

itoggle caption MittRomney.com

J.W. Marriott dines with his son Bill in a Hot Shoppe in March 1969. The elder Marriott was close to Mitt Romney's father, George. Dennis Brack /Landov hide caption

itoggle caption Dennis Brack /Landov

Rick Santorum told voters in Mandeville, La. on Wednesday that they were "not looking for someone who's the Etch A Sketch candidate." Sean Gardner /Reuters /Landov hide caption

itoggle caption Sean Gardner /Reuters /Landov

Restore Our Future, the superPAC supporting Mitt Romney, is running negative ads about Newt Gingrich in Ohio ahead of Super Tuesday on March 6, 2012. Restore Our Future hide caption

itoggle caption Restore Our Future