Harris talks of being bused to school during exchange with Biden over his record of praise for segregationist senators and his opposition to bussing as means of desegregation

Remarks come after Biden makes president's 'very fine people on both sides' defense of white supremacists the center of his campaign launch

Newly announced Democratic candidate for 2020 election says president's comments made him realize 'the threat to this nation was unlike any I had seen in this lifetime'