Health and Human Services Secretary Michael Leavitt said that health care professionals should not face retaliation from employers or from medical societies because they object to abortion.

"Freedom of conscience is not to be surrendered upon issuance of a medical degree," said Leavitt. "This nation was built on a foundation of free speech. The first principle of free speech is protected conscience."

Abortion is one of the most divisive issues in the United States and the Bush administration, which is conservative, is giving abortion opponents a boost with these protections.

The proposed rule, which applies to institutions receiving government money, would require as many as 584,000 employers ranging from major hospitals to doctors' offices and nursing homes to certify in writing that they are complying with several federal laws that protect the conscience rights of health care workers.

Violations could lead to a loss of government funding and legal action to recoup federal money already paid.

Abortion rights supporters served notice that they intend to challenge the new rule.