Rubio sharpens attacks after latest Trump win in White House race

By Doina Chiacu and Alana Wise WASHINGTON (Reuters) - Marco Rubio emerged from a razor-thin second-place finish in South Carolina's presidential primary on Sunday with the Republican field winnowed and his target clear: Donald Trump. Rubio squeaked by rival and U.S. Senate colleague Ted Cruz in a vote on Saturday that cemented the appeal of firebrand outsider Trump as well as the failure of a candidate representing one of America's political dynasties, Jeb Bush. The remaining Republican candidat