WASHINGTON — As President Bush ponders whether to allow federal funding for research using stem cells from discarded human embryos, Jewish ethicists and groups are debating the finer moral points of the issue.

On Monday, during a meeting with the president at the pope's summer residence, John Paul II told Bush to "reject practices that devalue and violate human life at any stage." The pope also voiced his opposition to creating human embryos for research purposes "destined to destruction in the process."

The president said he is weighing the issue very carefully and is taking his time before making a decision.

Like the president, some Jewish groups are still delaying a formal position, but most ethicists agree Jewish tradition allows embryos to be destroyed if the research has the potential to benefit society.

Admittedly, it's difficult to find traditional Jewish sources that address embryonic stem cell research directly, says Professor Paul Root Wolpe, an ethicist at the Center for Bioethics at the University of Pennsylvania. Instead, Jewish ethicists are extrapolating from the Jewish legal tradition and rabbinic commentaries.

Many authorities cite traditional imperative to heal, and the concept of pikuach nefesh — the responsibility to save human life, which overrides almost all other laws — to approve a broad range of medical experimentation.

Hadassah: The Women's Zionist Organization of America is in favor of embryonic stem cell research, as is the National Council of Jewish Women. The Jewish Council for Public Affairs has yet to take a formal stand on the issue.

A stem cell, which can be obtained from embryos as well as from such adult cells as bone marrow, has a unique capacity to renew itself and to develop into other specialized cell types.

Researchers use stem cells to repair or replace cells that are damaged or diseased. Those cells have the potential for treating such conditions as Parkinson's disease, Alzheimer's, diabetes, multiple sclerosis and heart disease.

A just-released National Institutes of Health report found that both embryonic stem cells and adult stem cells "present immense research opportunities for potential therapy." But while embryonic stem cells can proliferate indefinitely, adult stem cells cannot.

At issue for Bush is only the federal funding of embryonic stem cell research. He cannot place restrictions on private research that doesn't receive U.S. money.

Most religious groups and right-to-life proponents favor the use of adult stem cells in research and in treating disease, but there are some divisions over using stem cells obtained from discarded embryos, which the Catholic Church condemns.

There are also some divisions among those who favor embryonic stem cell research. President Clinton, who approved federal funding for embryonic stem cell research, said that only embryos that had already been created for in-vitro fertilization could be used — not embryos deliberately created for research purposes.

The NIH recommends federal funding should go only for research on frozen embryos that are destined to be discarded. However, some U.S. scientists are currently experimenting on human embryos created for research purposes.

Rabbi Aaron Mackler, professor of theology at Duquesne University in Pittsburgh, notes that using embryos taken from fertility clinics makes the case for research easier because those embryos already have been created for the purposes of in-vitro fertilization.

"There's potential life here, and we need to respect that and be cautious," he said.

Jewish tradition places minimal life value in early-stage embryos outside the womb since the Talmud defines any embryo up to 40 days old "as if it were mere fluid." Forty days roughly corresponds to the onset of "quickening," the first noticeable movement of a fetus in a womb.

In addition, the location of an embryo — that is, whether it is inside a woman's uterus or in a lab — also makes a difference.

Embryos that remain outside the womb have no chance to become children, and therefore it is a "mitzvah" to use those embryos for research, according to Rabbi Elliot Dorff, rector and professor of philosophy at the University of Judaism in Los Angeles.

"It's not only permitted, there is a Jewish mandate to do so," he added.

Dorff, who wrote a book on Jewish medical ethics, said that creating an embryo specifically to be a source of stem cells is permissible, but less morally justifiable.

Early this year, Bush asked the Department of Health and Human Services to review stem cell research. Government supervision of stem cell research could result in better research and quicker results, which would bolster the ethical argument for proceeding with federal funding, according to Ruth Macklin, professor of bioethics at the Albert Einstein College of Medicine in New York.

And Rabbi Moshe Tendler, professor of Jewish Medical Ethics at Yeshiva University in New York, called stem cell research "the hope of mankind."

"The only hope we have of understanding what's going on in the whole field of oncology, of cancer work, now resides in the stem cell research," he said at a recent event in Washington.

Tendler criticized a Senate bill that would stop the possibility of stem cell research.

"That I believe to be an evil that's being perpetrated on America," he said.

Recently, the Reform movement's Union of American Hebrew Congregations sent letters to Bush and Department of Health and Human Services Secretary Tommy Thompson in favor of "carefully regulated" federal funding of embryonic stem cell research.

Quoting Deuteronomy, the letter noted that Jewish tradition says that while only God can create life, God has charged humans with doing everything possible to preserve it.

"I have put before you this day life and death. Choose life, that you and your children may live," the letter said.

The Orthodox Union and Agudath Israel of America do not have formal positions on the issue. David Zwiebel, executive vice president for government and public affairs for the organization, suggested there would not be an ethical problem with using those embryos slated to be discarded but was unsure whether the group wanted to weigh in on a policy level about use of government funds for the research.

Bush has been weighing the issue for months. During the campaign and as recently as May, he said he would oppose federally funded research or experimentation on embryonic stem cells that requires the destruction of living human embryos.

One compromise might be to allow funding for research on stem cells derived from the approximately 100,000 surplus embryos — now frozen in fertility clinics around the country — but would ban research on anything beyond that.

Ari Fleischer, Bush's press secretary, said the president is carefully considering the different perspectives on the issue.

"The president is very aware that there is a balance on this issue, where there is so much potential for health and for breakthroughs," he said. "On the other hand, the president is very concerned about preserving a culture of life."