By Dan Griffiths
Laura Bush, the wife of President Bush, has defended her husband's decision to limit embryonic stem cell research.
Mrs Bush said her husband's policy took morality into account
She stepped into the debate after the Democratic presidential candidate, John Kerry, promised that he would lift Mr Bush's restrictions.
Embryonic stem cell research has always been a controversial topic in the US.
Scientists say it could lead to cures for many diseases, but it is at a very early stage and is strongly opposed by conservative religious groups.
The idea is that stem cells taken from embryos can be used to grow fresh human tissue.
The religious groups object because removing stem cells kills the embryo.
The Bush administration has placed limits on federal funding for the research.
Speaking at a meeting in Pennsylvania, Mrs Bush defended her husband's policy, which she said "makes it possible for researchers to explore the potential of stem cells while respecting the ethical and moral implications associated with this research".
She said the science is "very preliminary
right now, and the implication that cures for Alzheimer's are
around the corner is just not right".
Her comments come only days after Mr Kerry said that he would remove restrictions on the funding of stem cell research.
The issue is now turning into a hot election debate, with a clear distinction between the two candidates.
Recent opinion polls suggest that the idea is gaining acceptance among ordinary American voters, with a majority in favour of research.
And that is something the Democrats will be keen to seize on in the weeks ahead.