LANGHORNE, Pa. -- Laura Bush defended her husband's policy on embryonic stem cell research yesterday, calling Democratic rival John F. Kerry's criticism ''ridiculous" and accusing proponents of overstating the potential for medical breakthroughs.
''We don't even know that stem cell research will provide cures for anything, much less that it's very close" to yielding major advances, Bush said.
She weighed in on the highly charged political and scientific issue on the third anniversary of President Bush's decision to limit federal funding of embryonic stem cell research to only the 78 stem cell lines in existence Aug. 9, 2001.
Religious groups oppose the scientific work in which culling of stem cells kills embryos, equating that with abortion, and had urged Bush not to be the first president to fund the research -- even with limits.
Proponents of the science, including Ronald Reagan's widow, Nancy, and 58 Democrats and Republicans in the Senate say it could lead to cures to diseases such as diabetes and Alzheimer's.
Ronald Reagan suffered from the latter for a decade before his death June 5 due to related pneumonia.
Only a fraction of the initial 78 stem cell lines -- 21 at last count -- are yet available to researchers because of problems with the lines' growth or their ownership.
In March, a National Institutes of Health count cast doubt on how many ultimately would be usable.
Proponents say more than 100 new cell lines have been created worldwide since Bush's decision -- some with new techniques that may make them more scientifically useful -- and could be studied under more open rules. An exact count is not possible because private funding means much of the work is done without public scrutiny.
With polls indicating overwhelming support for the research, Kerry has promised to give scientists more freedom. He has described Bush's actions as a ban when what the president has done is limit the research.
''That's so ridiculous," Laura Bush said in an interview. ''It's one of the myths that start during a campaign."
Kerry spokesman Phil Singer said Bush's restrictions apply to 99.9 percent of potential stem cell lines that could be studied. ''If that's not a ban," he said, ''we don't know what is."
Laura Bush said Kerry was trying to make a political issue out of her husband's policy ''without saying what's right. I imagine he knows better."
Like others campaigning for the GOP ticket, Bush credited her husband with being the first president to use taxpayer money for the research. That is true, perhaps only because the science is so new. The policy of Bush's Democratic predecessor, Bill Clinton, allowed taxpayer money to be used in the research of any stem cell lines, but he never funded the nascent research. Bush invested $25 million in limited research.
Kerry's running mate, Senator John Edwards of North Carolina, said yesterday marked ''a sad anniversary" because the Bush administration ''put restrictions in place that dramatically undermine our efforts to find cures for diseases."
Edwards, in a conference call with reporters, said Kerry would reverse Bush's policy, invest $100 million for research, and establish ethical guidelines for the science.
In a speech to the Pennsylvania Medical Society, which endorsed her husband, Bush said policy makers must be aware of the ''ethical and moral implications" of the research.
''I hope that stem cell research will yield cures," she said. ''But I know that embryonic stem cell research is very preliminary right now and the implication that cures for Alzheimer's are around the corner is just not right."
While Bush's actions forbid federal dollars, it does not stop private funding of stem cell research. In an editorial in The New England Journal of Medicine, Dr. George Q. Daley, a leading stem cell researcher, said that research has struggled without federal funds.