new york probability republican front-runner donald trump win party presidential nomination drop sharply past week likelihood broke convention potentially choose another candidate rise accord online predictions market predictit trump probability win nomination fell 44 percent friday 67 percent week ago accord website run victoria university wellington new zealand republican rival ted cruz u.s. senator texas rise 34 percent 14 percent period probability republicans broke convention decide nominee nov. election jump 69 percent 43 percent week ago accord predictit online predictions market users place money think win election many users unite state celebrity businessman trump face pressure take serious approach presidential campaign supporters worry string recent missteps controversial comment may last damage cruz win tuesday primary wisconsin would make hard trump reach 1,237 delegate need clinch nomination republican national convention july trump win enough delegate party face prospect hold contest broke convention party leaders try negotiate nominate compromise candidate trump 's probability win nomination drop predictit