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Heath and Human Services Secretary Tommy Thompson praised President Bush's decision to provide limited funding for embryonic stem cell research as brave.

"Make no mistake: This is a bold step forward," Thompson told a Friday news conference at the National Institutes of Heath in Bethesda, Md. He called Bush's decision to use federal funds for research on existing stem cell lines "courageous and compassionate."

Thompson — who had urged the president to provide federal funds for all stem cell research — said work is underway on creating a registry for the lines that are already available. He told reporters he believes that the number of existing lines will grow as the government learns of more.

Bush's Thursday night announcement on one of the most crucial issues in his presidency prompted mixed reactions. The debate has sparked a moral and ethical debate about the destruction of embryos in fertility clinics to harvest stem cells.

Supporters of embryonic stem cell research argue it could provide extensive benefits for life-threatening diseases and save lives.  They also argue that the days-old clusters of cells in question are discarded anyway, so they advocate putting them to scientific use.

Opponents argue that harvesting these cells requires the destruction of human life and is a moral abomination.  They point to the value of using stem cells from placentas and umbilical cords as an equally viable option.

Roman Catholic leaders condemned the president's decision as "morally unacceptable." Conservative Protestants said they were disappointed but encouraged by Bush's thoughtful approach.

"The fact that he is not putting federal funds in the support of killing additional babies is a very critical line not crossed," said Richard Land, president of the Southern Baptists' Ethics and Religious Liberty Commission.

Bush announced that he would support federal funding for the research, but only on existing lines of embryonic stem cells, restricting research to cells from embryos that already have been destroyed.

But Dr. John Gearhart, a researcher at John Hopkins University in Baltimore, said he was disappointed Bush limited funding only to 60 or so lines of existing stem cells. He said it could slow research unless new stem cell lines are drawn from additional embryos.

"This limitation the president has put on this is going to delay, I believe substantially, the progress we need to make," Gearhart told NBC's Today show.

And some laboratory scientists at the National Institutes of Health continue to accuse the president of being "misleading" in his characterization of the number of stem cell lines. The researchers at the labs say that scientific journals and literature list less than a dozen existing stem cell lines and that some of these lines are controlled by private companies that would not seek federal funding.

In addition, they say, some stem cell lines that may exist around the world would not be eligible at the NIH because of an "informed consent" provision adopted during the Clinton administration. "Informed consent" requires that U.S. scientists only conduct research on embryonic stem cell lines derived from couples that have given written consent, and many researchers around the world do not face this consent provision.

But White House counselor Karen Hughes said, "all of the stem cell research currently being done on mice is being done on only five stem cell lines. We're talking about 60 stem cell lines here. I think there's enough work to keep the scientific community very busy and we hope certainly to produce cures."

Thompson said the 60 cell lines were adequate to push research ahead and pursue possible new cures for diseases as diverse as diabetes and Parkinson's. "We feel that that is enough to really carry on the research," Thompson said.

And on Capitol Hill, the president's decision was met with praise in some quarters and with caution and disappointment in others.

Sen. Edward M. Kennedy, D-Mass., a supporter of research, welcomed Bush's decision as "an important step forward." But, he added, "it doesn't go far enough to fulfill the lifesaving potential of this promising new medical research."

"We should take a lot of time to think through the steps that we're proceeding down before we rapidly move down this road ... This is a new world for us," said Sen. Sam Brownback, R-Kan., a leader of abortion opponents concerned that embryos are destroyed for stem cell research.

And Sen. Rick Santorum, a Republican of Pennsylvania, said, "While the president put forward the best compromise, I continue to respectfully disagree with any funding for embryonic stem cell research."

'I Pray It Is the Right One'

After weighing the issue for months, Bush addressed the nation Thursday night to announce his decision.

"I have made this decision with great care and I pray it is the right one," Bush said in the first prime-time speech of his presidency.

"Like a snowflake, each of these embryos is unique," Bush said, "with the unique genetic potential of an individual human being."

Citing the promise of breakthroughs in fighting diseases such as Alzheimer's and diabetes, Bush said he would approve federal funding, but only for existing lines of embryonic stem cells. That would restrict research to cells from embryos that already have been destroyed.

The president, an opponent of abortion, said he would prohibit the use of federal funds to create any new lines of human embryonic stem cells. He said it was important that "we pay attention to the moral concerns of the new frontier."

Bush also said he was creating a president's council — led by biomedical ethicist Leon Kass of the University of Chicago — to monitor the research and recommend guidelines and regulations. Other ethicists, scientists, doctors, lawyers and theologians will also be named to the council.

The Associated Press contributed to this report.