Haraz N. Ghanbari/AP Photo

Marco Rubio is leading the GOP charge on immigration reform, but he says new policies won't work without changing President Obama's health-reform law.

In a radio interview with Rush Limbaugh today, Rubio warned that if undocumented immigrants are granted the opportunity to gain legal status, too many people could start getting health subsidies from the government under the "Obamacare" law.

"'Obamacare' is the only federal benefit [for] which you qualify not because you have a green card, but only because you're lawfully present," Rubio said. "If 'Obamacare is available to 11 million people, it blows a hole in our budget" and makes reform unworkable.

Obamacare, officially the Affordable Care Act, subjects aliens "who are lawfully present in the United States" to the individual mandate and makes them eligible to receive government help, the Congressional Research Service noted in a 2011 report.

While a "green card" grants permanent legal residency, lawful aliens include immigrants legally admitted to the United States who do not have a green card, refugees and those seeking asylum, and people who have not immigrated to the United Sates but are here temporarily (including temporary workers).

A recent Senate proposal would make applicants for legal-resident status ineligible for federal benefits during a probationary period as they apply.

Multiple immigration proposals are being unveiled and both Republicans and Democrats have signaled a desire to allow undocumented immigrants a chance to stay legally.

Rubio also said an immigration reform bill must ensure that certain border-security benchmarks are met, only allowing resident status when the border has become secure.

He said that without those assurances, 'We are not going to have a bill that [includes] the opportunity to apply for a green card."