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US lawmakers were last week gathering support for legislation that would ease federal restrictions on funding for embryonic stem-cell research.

Public polls favour the bill, which passed by a large bipartisan majority in the House of Representatives on 24 May (see Nature 435, 544–545; 2005). But President George W. Bush is dead against it. That left many senators in the Republican party in a quandary: how could they back a popular measure without alienating pro-life voters and the US president?

Into this fray stepped William Hurlbut, a consulting professor in human biology at Stanford University who serves on the President's Council on Bioethics. At a Senate hearing on 12 July, Hurlbut told lawmakers to back research into the creation of embryo-like entities that have been engineered to lack the capacity to develop into human babies, for example by mutating certain genes.

Hurlbut has proposed that scientists create these entities in a process he calls “altered nuclear transfer”, to distinguish it from somatic cell nuclear transfer, which scientists use to create human embryos from which stem cells can be extracted.

Such entities lack the moral status of human embryos, argues Hurlbut, and so could be used for research with fewer ethical objections. “We should find a way to go forward with our biomedical research that gathers in our whole nation,” he told the Senate.

Although Hurlbut sees himself as a unifying force, many stem-cell researchers are worried. His proposal has not been tested, and the idea of purposely creating defective embryos has met with serious objections from ethicists.

But it is a gift for politicians who are undecided about stem-cell research. Senate leaders, encouraged by the White House, have begun pushing for laws backing such alternatives to embryonic stem-cell research. The proposals threaten to erode support for the measure to loosen funding restrictions on stem-cell research itself.

William Hurlbut believes embryo-like entities offer a way forward for stem-cell research. Credit: S. SENNE/AP

Despite opposing the use of embryos for stem-cell research, Hurlbut describes himself as “very pro-science”. He attended Stanford Medical School, but abandoned plans to practise medicine when his first child was born with severe brain damage.

As a result, Hurlbut decided to devote his career to teaching and studying the ethics of biomedicine. One of his heroes became Saint Francis of Assisi, whose life of poverty was characterized by a love of nature. “I thought, this is exactly what the world needs right now,” Hurlbut says. “We were ravaging the natural world, and it was obvious that we were ramping up to ravage and reorder the human body as well.”

Joining the President's Council on Bioethics in 2002, Hurlbut says he felt torn between the supporters and opponents of embryonic stem-cell research, and proposed altered nuclear transfer as a way to bridge the divide.

He warns that the debate over stem cells could be the first of a series of battles over the use of powerful techniques in developmental biology. He believes scientists must forge harmony with their opponents or risk losing support and funding for their work.

“If we don't have a solid frame from which we can go forward, there's just going to be an endless series of bitter disputes,” Hurlbut says. “I'm trying to provide one little island of unity in a large sea of controversy.”

As Nature went to press, negotiators were still trying to decide how to bring the stem-cell legislation before the full Senate for a vote this week.