The former South Carolina Republican senator said on ABC that the report “presents a staggering cost of another amnesty.” “The bill that’s being presented is unfair to those who came here legally,” he added.

The legislation aims to enhance border security, create an agricultural guest-worker program, overhaul the legal immigration system and provide a path to citizenship for an estimated 11 million undocumented immigrants.

DeMint has long been a staunch opponent of giving illegal immigrants any legal status.

DeMint also dismissed Congressional Budget Office (CBO) estimates that show immigration reform will increase economic growth. “CBO said ObamaCare wouldn’t cost us anything,” DeMint said, adding that “they’re basically puppets of the Congress.”

Sen. Marco RubioMarco RubioBush ethics lawyer: Congress must tell Trump not to fire Mueller The private alternative to the National Flood Insurance Program  Cruz offers bill to weaken labor board's power MORE (R-Fla.), pushed back against the Heritage Foundation report last month. A similar report helped derail immigration reform six years ago by undercutting conservative support.

Rubio, one of the so-called “Gang of Eight” that negotiated the Senate bill, argued that the bill's effects should be taken on the whole and not just looked at from what it would cost the government. "This will be a net positive for our country now and for the future."