By going through the tax system, the GOP has figured out a way to undermine President Barack Obama's executive order, which was designed to protect the approximately 4 million undocumented U.S. immigrants from deportation.

Republicans in Congress will seek to keep those Latino immigrants from becoming retroactively eligible to claim the Earned Income Tax Credit.

According to the nonpartisan Joint Committee on Taxation, the Republican-sponsored legislation would end up saving the government $2.1 billion.

This new attack on immigration rights is focused on the argument that Obama's executive order will impose a heavy financial burden on federal, state and local governments.

Republican Sen. Charles Grassley of Iowa, the lead author of the bill, said the measure "is not meant to be part of the immigration debate.''

As reported in USA Today, Grassley said, "It's just part of correcting what the president has put in place when he legalized people through his November action.''

The executive order would allow for documented immigrants to receive Social Security cards needed in order to file tax returns.

Problems arise, according to cosponsors of the legislation, because of the fact the Internal Revenue Service allows people who have recently received a Social Security number to file amended returns claiming an Earned Income Tax Credit, a refundable credit claimed by low- to moderate-income working people, for up to three prior years.

Grassley's office estimates that the average credit in 2012 was just over $2,300 and the maximum available credit in 2014 is $6,143.

According to Daniel Costa, director of immigration law and policy research for the Economic Policy Institute, the median annual salary of undocumented four-member immigrant families was around $40,578 last year.

Costa estimates that a family in that range would qualify for an EITC of about $2,000.