Charles Schumer, Marco Rubio,  John McCain

Authors of the newly released Senate immigration bill touted the package Thursday as a “bipartisan breakthrough” in advance of a critical hearing, as opponents began to organize against the bill — claiming it doesn’t do enough to enforce existing immigration law.

Sen. Marco Rubio, R-Fla., who has put his conservative reputation on the line with his involvement in writing the bill, took to the floor late Thursday afternoon to defend it. Though critics have homed in on the bill’s pathway to citizenship for illegal immigrants, Rubio said the package would also fix a “broken” legal immigration system so that foreign students trained in America would not be sent back home once they’ve learned their skills.