Aug 31, 9:06 PM EDT Castor wins Senate nomination; Martinez leads GOP race By STEVEN WINE Associated Press Writer MIAMI (AP) -- Betty Castor won the Democratic nomination Tuesday for the Senate seat being vacated by a retiring Bob Graham, and Mel Martinez led the Republican race in a primary election that tested Florida's much-maligned voting system. Castor, a former state education commissioner and university president, led U.S. Rep. Peter Deutsch by nearly a 3-to-1 margin with half the precincts reporting. Castro had 64 percent of the votes to 23 percent for Deutsch. Miami-Dade County Mayor Alex Penelas was third...