Here is a comparison of what the leading candidates say about stem cell research on their "issues" pages of their campaign web sites. These are just excerpts but I have provided the links if you want to read all of what they say. I assume that these issue statements were carefully decided upon and carefully crafted to appeal and communicate to a national audience.
Clinton: Hillary supports stem cell research but the topic does not rise to the level of including it in her official issue statements. **UPDATE** Sorry I did not notice this before. The following is included under "Comprehensive Government Reform": Rescind the ban on ethical embryonic stem cell research.
Obama: Ditto for Obama although he does talk about funding biomedical research.
McCain: Stem cell research offers tremendous hope for those suffering from a variety of deadly diseases - hope for both cures and life-extending treatments. However, the compassion to relieve suffering and to cure deadly disease cannot erode moral and ethical principles. For this reason, John McCain opposes the intentional creation of human embryos for research purposes. … As president, John McCain will strongly support funding for promising research programs, including amniotic fluid and adult stem cell research and other types of scientific study that do not involve the use of human embryos.
Huckabee: I am opposed to research on embryonic stem cells.
Other recent comparison posts of mine: abortion, immigration, marriage, energy/environment, federal spending