Washington

Almost three years after President Bush laid down a policy restricting the use of public funds in embryonic stem-cell research, calls are growing for the White House to revisit the rules.

On 8 May, Nancy Reagan, former first lady and an icon of Bush's Republican party, spoke publicly for the first time of her support for stem-cell research. She had written letters in favour of it before but her speech, at a benefit dinner in Los Angeles for the Juvenile Diabetes Research Foundation, is seen by supporters of the research as a significant public-relations breakthrough.

Reagan said that she had been moved to support research using stem cells through watching her husband succumb to Alzheimer's disease. “Ronnie's long journey has finally taken him to a place where I can no longer reach him,” she said. “We cannot share the wonderful memories of our 52 years together, and I think that is the hardest part. I am determined to do whatever I can to save other families from this pain.”

A few days earlier, on 4 May, the majority leader in the Senate, Bill Frist (Republican, Tennessee), said he thought the time had come to review President Bush's policy. The rules let researchers use public funds to work on embryonic stem-cell lines only if the lines were derived before the day the policy was announced — 9 August 2001.

“Momentum is building in the research done, and in Congress,” says a Republican staff member for the Senate Committee on Appropriations.

Last month, 206 members of Congress, including 36 Republicans, sent a letter to President Bush asking him to expand his policy. Among its signatories were members of Congress who had previously opposed the research, such as lawmaker Dana Rohrabacher (Republican, California). Rohrabacher told reporters that he had changed his mind after hearing from patients who hope the reasearch will help cure their diseases.

A similar letter is circulating in the Senate, and White House officials have indicated that the president will meet with the authors of the House letter.

Although the National Institutes of Health estimated that researchers would be able to work on 78 stem-cell lines, fewer than 20 are actually available today. And biologists have raised doubts about the suitability of these for clinical research.