WASHINGTON - In an early indicator of how congressional Republicans will legislate on immigration, House GOP leaders are expanding an inquiry into an enforcement program that allows employers to check the immigration status of employees.

The E-Verify program has long been championed by Rep. Elton Gallegly, R-Calif., chairman of the House subcommittee on immigration policy and enforcement, which will hold a hearing about it today.

Many business owners believe that Gallegly and other House Republicans want to make E-Verify, currently a voluntary program for companies, mandatory.

Critics - many of them farmers - warn that such a move could destabilize the agricultural economy, which is heavily dependent on undocumented immigrants, and jeopardize millions of jobs held by U.S. citizens that are upstream and downstream of farm labor.

Supporters of E-Verify say that, with minimal effort, it ensures that jobs are filled only by U.S. citizens and those foreigners legally authorized to work.

After he was named chairman of the immigration subcommittee, Gallegly noted that "making E-Verify universally mandatory would ease the cumbersome and easily manipulated I-9 process employers now use to screen employees. It would also greatly reduce the number of illegal immigrants in the American workforce."

Gallegly was referring to a form known as the I-9 that employers are required to have employees fill out. It requires documentation that the employees are allowed to seek work, including a Social Security number and other documentation pertaining to employment authorization.

With E-Verify, employers run the information through federal databases to identify people not legally authorized to work.