For Trump backers, ethnicity plays no factor. "I don't think Cuban, I think American," said former Hialeah Mayor Julio Martinez, who for two weeks has held a Trump campaign sign outside an early voting site just blocks from where Rubio last week implored Hispanics to vote for him in Tuesday's presidential primary. Perched in a lawn chair outside the John F. Kennedy Library, holding a "The Silent Majority Stands with Trump" sign, Martinez said he was backing Trump because there was "nobody better suited" to fixing the economy. "The worst problem the United States has today is the economy," he...