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WASHINGTON -- President Obama will sign an executive order Monday lifting restrictions on federal funding for embryonic stem-cell research, administration officials said Friday.

The order, which will fulfill a campaign pledge, will reverse limits put into place by then-President George W. Bush in August 2001.

Research on embryonic stem cells is considered promising, and could lead to treatments for a range of ailments, including Parkinson's disease, diabetes and spinal-cord injuries, scientists say. Embryonic cells are considered particularly potent because they can develop into any type of tissue.

But it is controversial because it involves the destruction of days-old human embryos. Opponents say the research requires killing one life to potentially save another, and they have focused on the promise of research using adult stem cells, which has made advances in recent years.

Some politicians who oppose legalized abortion support embryonic stem-cell research. But others say life begins at conception and thus the research requires the taking of human life.

The embryos used for the research typically are donated by couples who wound up creating more than they needed during fertility treatments and would otherwise be thrown away. Each embryo can yield one stem-cell line, which can continue replicating indefinitely.

The debate has never been about the legality of stem-cell research, which is legal in the U.S. At issue is whether the science qualifies for federal funding.

In a closely watched decision early in his presidency, Mr. Bush allowed federal funding for stem-cell research but limited it to stem-cell lines already in place at the time of his announcement, on Aug. 9, 2001. Mr. Bush said he didn't want a federal incentive for more embryos to be destroyed.

Twenty-one lines then in existence qualified for funding, but researchers and patient-advocacy groups have complained that they were inadequate and not all of high quality.

Mr. Obama's executive order will lift the Bush restrictions and allow National Institutes of Health funding for all stem-cell lines. The order will be signed at a White House event Monday.

As written, the law gives the administration discretion in determining whether the research qualifies for funding. Congress twice passed legislation overturning the ban, but Mr. Bush vetoed it both times. Supporters didn't have the votes needed to override the veto.

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