U.S. President Barack Obama speaks during a campaign event in support of U.S. Democratic presidential candidate Hillary Clinton in Philadelphia, Pennsylvania, U.S., September 13, 2016. REUTERS/Carlos Barria

U.S. President Barack Obama speaks during a campaign event in support of U.S. Democratic presidential candidate Hillary Clinton in Philadelphia, Pennsylvania, U.S., September 13, 2016. REUTERS/Carlos Barria

U.S. President Barack Obama speaks during a campaign event in support of U.S. Democratic presidential candidate Hillary Clinton in Philadelphia, Pennsylvania, U.S., September 13, 2016. REUTERS/Carlos Barria

September 13, 2016 4:15 PM (UTC+8)