CNN

As the immigration debate continues in Congress, family members touch hands through a U.S.-Mexico border fence in San Ysidro, California.

WASHINGTON (CNN) - Border security provisions included in the immigration bill currently stalled in the Senate can be enforced under current laws, nine Republican senators said, and they urged President Bush on Tuesday to order their enforcement - regardless of whether the bill passes.

"The bill assumes that several critical border security benchmarks can be achieved within 18 months. These security triggers are already authorized under current law," the senators said in a letter.

"We believe these enforcement measures are vital and should not wait until Congress passes additional immigration reforms. Securing the border is best way to restore trust with the American people and facilitate future improvements of our immigration policy."

The letter is signed by Jim DeMint, R-South Carolina.; Tom Coburn, R-Oklahoma.; Mike Enzi, R-Wyoming; David Vitter, R-Louisiana.; Jim Inhofe, R-Oklahoma.; Jim Bunning, R-Kentucky; Charles Grassley, R-Iowa; John Ensign, R-Nevada; and Jeff Sessions, R-Alabama.

They said the bill calls for several security "benchmarks" that are already in place or called for under current laws, including:

– Hiring 18,000 border patrol agents. The senators noted that Bush announced in May his commitment to hiring 6,000 additional agents by the end of 2008, which would boost the number of agents to 18,000.

– Installing 200 miles of vehicle barriers, 370 miles of fencing, and 70 ground-based radar and camera towers, and using unmanned aerial vehicles. The senators said these numbers are less than what is already provided for under the Secure Fence Act, signed into law in 2006.

– Ending "catch-and-release" practices along the borders, and providing 27,500 beds for immigrant detainees. The senators said the Department of Homeland Security has announced these steps are already are in place.

– Using secure identification documents with photo and biometric information and establishing an employment verification system to determine work eligibility. The senators said the Secure ID Act, signed into law in 2005, calls for the photo and biometric information, while the Department of Homeland Security appropriations bill for fiscal year 2007 provides $113 million to expand the Basic Pilot/Employment Eligibility Verification system to become a national employment database.