Chicago [US], August 21 (ANI): Former US president Barack Obama took centre stage at a Democratic National Convention keynote speech urging Americans to back Kamala Harris in her presidential bid against Republican candidate Donald Trump. Speaking after his wife Michelle Obama on Tuesday (local time), the former US president recalled that Harris in her capacity as the attorney general of California had stood up for children who had been victims of sexual abuse. “Kamala Harris is ready for the job,” Obama said noting that she fought big banks and for-profit colleges, “securing billions of dolla…