After two successive elections that have exposed the Republican Party to ridicule for its lack of diversity and narrow demographic appeal, the GOP suddenly finds itself with an unexpected bounty. From the West Coast to the East Coast, in some of the smallest and largest states in the nation, the party is currently fielding an unusually diverse crop of serious statewide candidates drawn from the seemingly endless list of constituencies the GOP lost in 2008—notably women, Latinos, African Americans, Asian Americans and young people. Electing just a few of these prospects would give the party a dramatic facelift and go...