Groups opposed to illegal immigration are mobilizing to ensure that the massive economic stimulus package under consideration in Congress contains provisions to protect American workers.

At a time of rising unemployment, the federal government should focus on creating jobs that will be filled by American citizens, not illegal immigrants, the groups say.

The $819 billion economic stimulus bill approved by the House last month included two provisions related to the E-verify program – an electronic tool that allows employers to verify the legal work status of potential employees.

Two amendments were added to the bill that passed on a party-line vote. One, from Rep. Ken Calvert, R-Riverside, reauthorizes the E-Verify program for four years. The other, from Rep. Jack Kingston, R-Georgia, requires all contractors receiving stimulus funds to verify that their employees are legally authorized to work in the United States.

As the Senate takes up stimulus legislation, Republican lawmakers and anti-illegal-immigration groups are working to include the worker verification requirements in the bill.

"E-Verify is the hinge on which all immigration enforcement and deterrence swings," said Rick Oltman, spokesman for Californians for Population Stabilization. "If you can reliably tell the people of the world that there is no job for you in America because we are checking, that will have an enormous deterrent effect."

E-Verify has been offered free to all employers on a voluntary basis since 2004. As of Jan. 8, about 100,000 employers were enrolled in the program, according to U.S. Citizenship and Immigration Services. The agency operates the program in partnership with the Social Security Administration.