Editor's note: CNN and CBS News are reporting that the White House is on lockdown and the cause is unknown. President Obama is reportedly inside the building. We're watching for more information and confirmation. - Rebecca
The Executive Office of the President (EOPOTUS or EOP) consists of the immediate staff of the current President of the United States and multiple levels of support staff reporting to the President. The EOP is headed by the White House Chief of Staff, currently Denis McDonough. The size of the White House staff has increased dramatically since 1939, and has grown to include an array of policy experts in various fields.