A senior adviser of former US Vice President and Democratic presidential hopeful Joe Biden was knocked to the ground during a rally in Detroit on Monday. In a scuffle with environmental protesters in the midst of Biden's remarks, Symone Sanders was knocked over, but wasn't hurt. The large rally was interrupted repeatedly by protesters who railed against Biden's support of the North American Free Trade Agreement (NAFTA) and his reluctance to embrace sweeping environmental proposals outlined in the so-called Green New Deal. (AP)