From the President's speech discussing the veto of H.R. 810.
"Like all Americans, I believe our nation must vigorously pursue the tremendous possibility that science offers to cure disease and improve the lives of millions... Yet we must also remember that embryonic stem cells come from human embryos that are destroyed for their cells. Each of these human embryos is a unique human life with inherent dignity and matchless value... If this bill would have become law, American taxpayers would, for the first time in our history, be compelled to fund the deliberate destruction of human embryos. And I'm not going to allow it." (Read the full speech here.)
The President gave this speech to, among others, families of "snowflake children," children who were frozen while still embryos, but have since been adopted and carried to full-term by their adoptive parents. Learn more about embryo adoption here.