The set of principles agreed to by the four Democratic and four Republican senators â¿¿ the Republicans are Rubio, John McCain of Arizona, Lindsey Graham of South Carolina and Jeff Flake of Arizona â¿¿ would create a pathway to citizenship for illegal immigrants. But that pathway would be contingent on securing the border and tracking people living in the U.S. on visas. It also would include changes to the legal immigration system, the noncitizen or "guest" worker programs and requirements for employer verification of immigration status.

Rubio, the son of Cuban-American immigrants, has argued that the system is broken and amounts to a de facto amnesty, with millions of people living in the U.S. without any chance of gaining legal status.

His proposal would include a number of triggers before illegal immigrants could apply for a green card. They would need to register with the federal government and pay back taxes and fines to qualify for a work permit. They would be ineligible for any federal benefits and would need to begin a long process of earning their citizenship â¿¿ essentially getting in the back of the line.

"We have to deal with it in a way that's compassionate but also responsible," Rubio said in an interview with Fox News host Bill O'Reilly.

Republicans have tried this before. In 2007, Republicans led by McCain tried and failed to adopt comprehensive immigration reform under President George W. Bush. In the years since, Democratic efforts to pass the DREAM Act, which would offer citizenship to young illegal immigrants who were brought into the country by their parents, failed to pass muster.

During the 2012 presidential primary campaign, Republican Mitt Romney opposed the DREAM â¿¿ Development, Relief and Education for Alien Minors â¿¿ Act and emphasized his support for a border fence and a policy he described as "self-deportation." The hard-line approach may have helped Romney fend off Republican challengers but those positions later hurt him with Latinos in the general election against President Barack Obama.

If you liked this article you might like

What's Behind the Surge in Energy Stocks

Hillary Clinton Says Prosecuting Individuals is Key to Wall Street Reform