By Caren Bohan
WASHINGTON (Reuters) - The second-ranking Senate Republican on Wednesday unveiled a proposal to significantly tighten security on the U.S.-Mexico border before giving undocumented workers legal status in the broad immigration bill being considered in the U.S. Senate.
The proposal from Senator John Cornyn of Texas, a skeptic of the bill that would grant legal status to some 11 million undocumented immigrants, would require the Department of Homeland Security to have surveillance over the entire U.S.-Mexico border and meet a benchmark of apprehending at least 90 percent of people trying to cross the border illegally.
Cornyn would tie achievement of the benchmarks to the plan to give permanent legal status to undocumented immigrants. Many immigrants' rights groups oppose such provisions, saying they would erode the path to citizenship at the heart of the bill.
Cornyn's amendment would also expand the use of biometric equipment to track foreigners leaving the country.
As Cornyn outlined his amendment in an opinion piece in the Dallas Morning News on Wednesday, he said the immigration bill had "some positives" but that its border security provisions ran the risk of amounting to "meaningless promises."
The bill before the Senate would authorize billions in new spending on border security and revamp visa programs to allow employers to hire more high- and low-skilled workers from abroad.
An aide to Florida Senator Marco Rubio, one of the bill's authors, said Rubio's staff has been "working closely with Cornyn's office" on parts of the amendment for weeks. Rubio, who is popular with the conservative tea party movement, is playing a lead role in courting Republican votes for the immigration bill.
Rubio was among several Senate Republicans who were scheduled to meet on Wednesday with conservative House of Representatives Republicans to discuss the immigration issue.
Comprehensive immigration is expected to face its biggest challenge in the Republican-led House, where many conservatives view the provision to grant legal status to undocumented immigrants as amnesty to people who broke the law.
In addition to Rubio, Senators Jeff Flake of Arizona, Rand Paul of Kentucky, Ted Cruz of Texas, Mike Lee of Utah and Jeff Sessions of Alabama were also scheduled to attend the meeting with House Republicans.
Flake and Rubio are members of the Senate "Gang of Eight" that wrote the immigration bill. Paul has signaled he is open to supporting the bill but wants to see stronger border-security provisions and other changes.
Cruz and Lee are both skeptics of the immigration bill and Sessions is one of the Senate's most ardent opponents the comprehensive legislation.
(Additional reporting by Richard Cowan; Editing by Vicki Allen)