Secret Service director Julia Pierson enters a hearing room in April to answer questions before a closed meeting of the Senate homeland security committee in Washington. Today, Pierson will appear before a House committee to respond to questions about White House security breaches. Cliff Owen/AP hide caption

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A Secret Service police officer stands near an entrance to the White House complex during an evacuation, minutes after President Barack Obama departed Washington for Camp David aboard Marine One. A man scaled a fence and reached the residence last night. Evan Vucci/AP hide caption

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Mark Sullivan, Director of the United States Secret Service, at a hearing of the Senate Homeland Security and Government Affairs Committee in May of 2012. Brendan Smialowski /AFP/Getty Images hide caption

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Before the vote, GOP nominee Mitt Romney and his running mate (Rep. Paul Ryan, in the background) were guarded by watchful Secret Service agents. After results came in, the agents quickly disappeared. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images