Sen. Marco Rubio is preparing to offer an amendment to the "Gang of Eight" immigration bill he helped negotiate to strengthen provisions that would prevent former illegal immigrants from receiving federal benefits.

The Florida Republican is collaborating on this proposal with Sen. Orrin Hatch of Utah, the top Republican on the Senate Finance Committee. Details of the amendment were not yet available. But Rubio said the measure would be designed to strengthen the principles of comprehensive reform legislation the bipartisan "Gang of Eight" authored, which included prohibiting millions of newly legalized immigrant residents from obtaining federal assistance -- such as Obamacare subsidies -- and burdening U.S. taxpayers.

"I'm working with Sen. Hatch," Rubio told The Washington Examiner Wednesday. "I think if we went to the floor and argued the benefits side of this, it's going to be very difficult for people to oppose it."

"Why should the American people be paying for Obamacare subsidies for people that are not permanent residents of the United States. So that has to be fixed and we've got to take care of that part of it," Rubio said, adding that even legal non-citizen residents with green cards do not qualify for Medicare or Social Security during their first five years in the U.S.

Earlier this week, Rubio proposed an amendment to the Senate immigration bill to beef up a provision that requires former illegal immigrants to demonstrate English proficiency as a condition of advancing to permanent residency, and eventually, citizenship.

Whether to permit the newly legalized to access federal health care benefits is an issue that tripped up negotiations among members of a bipartisan immigration working group in the House. Unable to agree, the House group shelved the issue.

The Senate gang agreed to prohibit former undocumented immigrants from accessing benefits under the Affordable Care Act. But some Senate Republicans have expressed concerns about potential loopholes, and any Hatch-Rubio amendment would be designed to bolster the legislation's intent.