WASHINGTON — The Bush administration yesterday proposed stronger job protections for doctors and other health care workers who refuse to participate in abortions because of religious or moral objections.

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,” Mr. Leavitt said. “This nation was built on a foundation of free speech. The first principle of free speech is protected conscience.”

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 foes called it a victory for the First Amendment, but abortion rights supporters said they feared the rule could stretch the definition of abortion to include birth control, and served notice that they intend to challenge the administration.

“Women’s ability to manage their own health care is at risk of being compromised by politics and ideology,” the president of the Planned Parenthood Federation of America, Cecile Richards, said in a statement.

Abortion rights groups had complained that earlier drafts contained vague language that might block access to birth control, and they said the latest version has not addressed all of their concerns.

The rule “fails to give assurances that current laws about abortion will not be stretched to cover birth control,” the president of NARAL Pro-Choice America, Nancy Keenan, said.

But Tony Perkins, the president of the conservative Family Research Council, said it upholds basic constitutional freedoms.

“This proposal ensures that doctors and other medical personnel will retain the constitutional right to listen to their own conscience when it comes to performing or participating in an abortion,” Perkins said. “These regulations will ensure that pro-life medical personnel will not be forced to engage in the unconscionable killing of innocent human life.”