In a Spanish-language interview Sunday with the network Univision, Sen. Marco Rubio, the leading Republican on the Gang of Eight comprehensive immigration reform group, made his strongest statement yet that legalization of the nation’s estimated 11 million illegal immigrants must happen before any new border security or internal enforcement measures are in place, and will in no way be conditional on any security requirements. “Let’s be clear,” Rubio said. “Nobody is talking about preventing the legalization...