Arguing that private research has produced more than 60 genetically diverse stem cell colonies, or lines, that could reproduce themselves indefinitely, Bush said in a nationalized TV address, "I have concluded that we should allow federal funds to be used for research on these existing stem cell lines, where the life and death decision has already been made."

He added that the research would be limited to cells that had already been extracted, and that the government would not support the destruction of new embryos. As a result, research on stem cells extracted from spare embryos left over after in vitro fertilization cannot go ahead if it uses federal funds.

Proponents of embryonic stem cells research criticized Bush for closing the door on obtaining stem cells from embryos that have been created for in vitro fertilization but are not being used by couples. "There will be concern about the limits...

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