Employers across the U.S. are preparing to fire workers with questionable Social Security government identification numbers to avoid getting snagged in a Bush administration crackdown on illegal immigrants.

The Department of Homeland Security is expected to make public soon new rules for employers notified when their worker's name or Social Security number was flagged by the Social Security Administration.

The rule, as initially drafted, requires employers to fire people who cannot be verified as a legal worker and cannot resolve within 60 days why the name or Social Security number on their W-2 doesn't match the government's database.

Employers who do not comply could face fines of $250 to $10,000 per illegal worker and incident.

"There's a lot of fear and anxiety about what this rule is going to mean, particularly in the agricultural sector," said Craig Regelbrugge, spokesman for the American Nursery and Landscape Association and co-chairman of the Agriculture Coalition for Immigration Reform.

The Homeland Security Department says the new rule provides guidance to employers on how to deal with workers who receive no match letters and give those who comply "safe harbor" if illegal workers are found at their business in an investigation or raid, said Russ Knocke, Homeland Security department spokesman.

U.S. Immigration and Customs Enforcement, a division of the Homeland Security Department, "is going to be tough and aggressive in the enforcement of the law," Knocke said. "You are going to see more work site cases. And no more excuses."