From dealing with crises at home and abroad to winning his historic re-election bid against Mitt Romney, 2012 was a busy year for President Barack Obama. We've collected the most iconic images from the roller-coaster ride that was Obama's fourth year in office, as captured by photographers who have been on the scene for the most poignant moments, as well as the more light-hearted ones.Obama embraces Congresswoman Gabrielle Giffords as he arrives on the House floor to deliver his State of the Union address.