Two Republican presidential candidates, Rick Perry and John Huntsman, are boycotting a proposed Univision debate due to what they say were unethical journalistic practices in the way the Spanish-language media giant handled Sen. Marco Rubio, a vice-presidential shortlister. Other campaigns might soon join Perry and Huntsman, sources say. They made their announcement at the behest of three Florida Hispanic Republican lawmakers who noted that the senator’s office and Univision insiders said Univision publicized an embarrassing story about Rubio’s brother in law because he wouldn’t sit down for an interview on the show Al Punto, which has espoused a liberal line...