>> reporter: well, brianna, that moment between joe biden and kamala harris on school busing dominated the debate last week. and biden is now telling our colleague chris cuomo he was surprised it was kamala harris that leveled that attack against him and biden put this in personal terms, bringing up his son beau who passed away a few years ago and had served as attorney general of delaware and became friends with kamala harris while she was attorney general of california. take a listen to what biden had to tell us yesterday about that moment with kamala harris. >> were you prepared for them to come after you. >> i was prepared for them to come after me but not prepared for the person came at me that came at me -- she knew beau and knew me. but here is the deal, and i know and the good and bad news, the american people think they know me and they know me. >> reporter: now the harris campaign contends there was nothing personal but it was biden's record under scrutiny