US Democratic presidential candidate Bernie Sanders waves as he arrives on stage for the CNN Democratic Presidential Debate at the Brooklyn Navy Yard on April 14, 2016, in New York. Hillary Clinton and Bernie Sanders take their increasingly acrimonious battle for the Democratic White House nomination to a debate stage in Brooklyn on Thursday ahead of the key New York primary. / AFP / Jewel SAMAD (Photo credit should read JEWEL SAMAD/AFP via Getty Images)
