President Bush Wednesday will announce sweeping changes to U.S. immigration laws that could give legal status to millions of people already working in the country illegally. The president's plan is expected to face congressional opposition from members of his own party.

The new temporary worker program is designed to match U.S. employers with undocumented workers either already in the United States or waiting to emigrate.

It is an amnesty for illegal immigrants already working in America, as those who qualify would receive all U.S. employee benefits including minimum wage and legal protections.

The president's plan requires approval from Congress where it is likely to face criticism from conservative Republicans who say they do not want to reward lawbreakers who have entered the country illegally and are working without permission.

Administration officials say there is no link between the temporary worker program and U.S. citizenship. The plan also includes incentives for undocumented workers to return to their countries by increasing the number of U.S. green cards available for them to enter legally.

President Bush telephoned Mexican President Vicente Fox Wednesday ahead of the announcement. Mr. Fox has been pushing for U.S. immigration reform at a time when Washington needs Mexico's help improving border security and stopping drug trafficking.