Few issues are likely to generate more emotional opposition than federal funding of stem cell research. Handled wrongly, it could energize conservative opponents and derail Barack Obama's presidency. There is no question that we must move ahead, but caution is key.

Effective federal support for human embryonic stem cell research has been stalled for almost a decade and half. In late 1994, the National Institutes of Health accepted all of the recommendations of its Human Embryo Research Panel — on which I served — regarding federal support for embryonic stem cell research. But the election of a conservative Republican Congress that year doomed our suggestions. In 1996, the Dickey-Wicker Amendment prohibited federal funding for any research involving destruction of human embryos. While President Bush in 2001 authorized research using a small number of previously established stem cell lines, this initiative has had limited effect — only 22 lines of cells and modest funding have been made available.

Late last year, separate teams of Japanese and American researchers announced that they had produced pluripotent stem cells — which retain the ability to become any body cell — by using gene insertion technology that causes body cells to revert to embryonic status. This has been applauded by many, including religious conservatives, because it appears to obviate the need to destroy human embryos. Yet obstacles to effective research, and to potential cures, remain. The pluripotent stem cells created through this technology have, for example, a tendency to become cancer cells. This renders them too dangerous for transplants. Most researchers agree that we have to keep open multiple pathways, not least of all the proven method of producing cell lines from human embryos.

Obama should minimize opposition by following the lead President Bush established in 2001. In justifying his policy of funding research on a limited number of human embryonic stem cell lines, Bush stated that "the life and death decision" had already been made on the embryos used to create those lines.

This is true of thousands of frozen embryos stored in fertility clinics around the country. More than 500,000 embryos created by in vitro fertilization to help couples have children are being stored. A large percentage of those embryos will never be used, because the couples have succeeded in having children, have given up or have grown too old to try. There is very little market for embryo adoption, so most of these embryos are destined to be destroyed. Circumstances have rendered the "life and death" decision on them almost as certain as it was on the embryos used before 2001 to make the stem cell lines that were approved to receive federal research funding.

By executive order, Obama could authorize the NIH to invite couples who planned to discard their frozen embryos to donate them for research. The couples would have to affirm that they no longer intended to use the embryos and had already decided to destroy them. Instead of the embryos merely being thawed and incinerated, as happens today, their cells could be used to produce lines for stem cell research.

The moral parallel here is organ donation after death. In this case, the embryo's death is an unavoidable result of its creation and subsequent non-use for reproductive purposes. The production of stem cells from these embryos could easily be accomplished without federal support, and the resulting stem cells could be donated for federal research.

Like President Bush, Obama could limit federal research to embryos created for reproductive purposes and abandoned before the statement of his policy. There are more than enough of these embryos to create all the lines we need for research. Under such a policy, there would be no use of embryos created with the intent to use them in stem cell research.

Would this approach eliminate all opposition to human embryonic stem cell research? Probably not. Many Americans still oppose any destruction of human embryos. Yet by observing that this policy represents only an extension of the one established by his predecessor, and by stressing the beneficial use of embryos that would otherwise be destroyed, Obama could succeed in reducing the most vehement opposition to a manageable level.

Ronald M. Green serves pro bono as chair of the Ethics Advisory Board at Advanced Cell Technology, a company involved in stem cell research. In 1994, he was a member of the NIH's Human Embryo Research Panel, the first official body to recommend federal support for human embryonic stem cell research. He wrote this commentary for The Washington Post.