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Handout photo of President Obama reacting during briefing by counterterrorism chief and adviser Brennan at the White House

President Barack Obama reacts as Counterterrorism chief and adviser John Brennan briefs him at the White House on the details of the shootings at Sandy Hook Elementary School in Newtown, Connecticut, December 14, 2012, in this White House handout photo released January 4, 2013. The president later said during a television interview that this was "the worst day of his Presidency." REUTERS/Peter Souza/Official White House Photo/Handout (UNITED STATES - Tags: CRIME LAW POLITICS TPX IMAGES OF THE DAY) FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS

Obama's presidential highlights

A look at the memorable moments of President Barack Obama's time in office.