washington u.s. republican presidential hopeful marco rubio say staff safe washington campaign headquarter evacuate suspicious white powder glad campaign staff dc safe thank dc emergency personnel rubio say tweet campaign spokesman alex conant tell washington post substance find worker envelope around p.m. turn laundry detergent rubio campaign tuesday home state florida one five state hold primaries republican party suspicious substance find houston campaign headquarter u.s. republican presidential contender senator ted cruz last week determine non-toxic local media report say cite cruz campaign official clear rubio campaign office white powder scare