Pope Francis is embraced next to Mexican President Enrique Pena Nieto (L) and First Lady Angelica Rivera (R) at the airport in Ciudad Juarez, Chihuahua state, Mexico, on February 17, 2016, from where he will take off for Rome. Throngs gathered at Mexico's border with the United States on Wednesday for a huge mass with Pope Francis highlighting the plight of migrants -- a hot-button issue on the US presidential campaign trail.  AFP PHOTO/ RONALDO SCHEMIDT / AFP / RONALDO SCHEMIDT        (Photo credit should read RONALDO SCHEMIDT/AFP/Getty Images)