Hours before President Obama is set to deliver a major immigration speech, a key Republican senator blasted the president for reportedly opposing a requirement to shore up border security before legalizing up to 11 million illegal immigrants. Sen. Marco Rubio, R-Fla., one of four Republican senators involved in a bipartisan effort to craft immigration reform legislation, warned the president Tuesday against taking such a position. It was the first sign since the senators unveiled their guidelines a day earlier of friction between the two efforts. "I think that would be a terrible mistake," Rubio told Fox News. "We have a...