WASHINGTON – Senate Republicans dissatisfied with the border security measures contained in bipartisan immigration reform legislation are rallying around amendments intended to make it almost impossible for undocumented workers to make it across the southern border.

One proposal receiving substantial attention, offered by Sen. John Cornyn (R-Texas), rewrites a significant portion of the reform measure, pieced together by a bipartisan coalition known as the Group of Eight.

One of the bill’s authors, Sen. Marco Rubio (R-Fla.), has announced his support for the Cornyn measure. Sen. Mark Kirk (R-Ill.), who at one point was thought to be sympathetic to the bill now before the full Senate, indicated he will oppose the measure unless the Cornyn amendment, or something like it, is adopted.

The amendment, which Senate Democratic Leader Harry Reid, of Nevada, has characterized as “a poison pill” intended to undermine the legislation, prohibits the estimated 11 million illegal immigrants already in the country from obtaining any sort of legal permanent residency until the federal government meets stringent border enforcement goals, including a complete awareness of activity along the border and 98 percent of all illegal crossings are thwarted.

In addition, the Cornyn amendment requires the implementation of a biometric system to track visa holders to keep tabs on their comings and goings and the creation of an E-Verify system – also called for by Sen. Rob Portman (R-Ohio) – so employers can determine if prospective hires are in the country legally.

Again, under the measure, no one would be afforded any sort of legal status unless those programs are in place.

“Sen. Cornyn’s proposal would do exactly what proponents of the current legislation say they support – require border security first and then proceed with other reforms,” Kirk said. “The metrics are not unreasonable, the goals are not unobtainable and the amendment is not a ‘poison pill.’ As we move forward with consideration of this bill, I urge Democratic leaders to rethink a strategy that castigates those who seek true immigration reform and also consider border security a top national security priority.”

Cornyn, who titled his proposal the Requiring Enforcement, Security and safety while Upgrading Lawful Trade and travel Simultaneously (RESULTS) Amendment, said it is necessary to assure the American public that the federal government is serious about closing the border.

“Americans are tired of hearing endless border security promises without seeing any realistic mechanism for guaranteeing results,” Cornyn said. “My amendment would guarantee such a mechanism and it would guarantee the results that Washington has long promised but never delivered.”

Speaking on the Senate floor Wednesday, Cornyn added,The true poison pill would be the failure to take sensible measures by adopting measures like mine which are designed to solve the problem.”

As it currently stands, the bill, titled The Border Security, Economic Opportunity and Immigration Modernization Act of 2013, addresses border issues by requiring the Department of Homeland Security to provide Congress with a plan to maintain persistent surveillance along the border that would stop more than 90 percent of illegal entries. The department furthermore would be required to report to Congress on how effectively it is implementing its plan, any impediments to fulfilling the plan and what actions it will take to address such impediments.