The Senate opened an emotional debate Monday over whether to expand federal funding for embryonic stem cell research, with advocates trying to dramatize the human benefits of the complex procedure and opponents underscoring what they see as its moral cost.
The legislation's supporters argued that it could help transform medical science in the United States, with more than 100 million patients potentially benefiting from research that might develop cures or treatments for such conditions as diabetes, spinal cord injuries and Parkinson's disease.
"The debate on embryonic stem cell research is as important as any issue that has ever been before the United States Senate," said Sen. Arlen Specter (R-Pa.), a leading proponent of the bill, who noted that his struggle with Hodgkin's disease might have been eased if research had advanced more quickly.
Critics of the legislation agreed that the stakes were high, for far different reasons. They said that because the research involves the destruction of human embryos, it is immoral and should not be financed by the government.
Sen. Sam Brownback (R-Kan.) quoted Christian writer C.S. Lewis in calling the procedure an affront to human dignity: "If man chooses to treat himself as raw material, raw material he will be."
Activists on both sides of the issue mobilized for a lobbying drive before today's vote on the measure to ease restrictions President Bush imposed in 2001 on federal funding for embryonic stem cell research.
"A lot of people are twisting a lot of arms today," Specter said.
There is little doubt about the fate of the measure, which will probably unfold in rapid-fire succession over the next few days.
The bill, which has passed the House, is expected to clear the Senate and then go to the White House.
Bush is expected to follow through with his oft-repeated promise to veto the measure -- the first veto of his presidency.
Supporters say they probably do not have enough votes to override Bush's veto. They would need a two-thirds majority in each chamber.
Although forestalling a veto is clearly an uphill battle, some bill advocates are trying to bring pressure on the president to sign it.
Specter said Bush might receive a personal call from Nancy Reagan, who became an outspoken advocate for stem cell research after her husband, President Reagan, fell victim to Alzheimer's disease.
But in an official statement Monday on the Senate measure, the White House reiterated the veto promise.
"The bill would compel all American taxpayers to pay for research that relies on the intentional destruction of human embryos," the statement said.
Although a Bush veto would kill the bill in Congress for this year, proponents are encouraged that support for the measure has grown, even in a Republican-controlled Congress.
The debate will probably continue in election campaigns in 2006 and 2008.
"This issue is not going away," said Sen. Edward M. Kennedy (D-Mass.).
"There are some issues you can't get off the national agenda, and this is one of them."
Understanding the emotional power of the issue, proponents of the bill brought patients who potentially could benefit from such research to a Capitol Hill news conference Monday.
Toni Bethea, 10, who was diagnosed with diabetes five years ago, said her message to the Senate's 100 members was this: "Think of me when they vote on the stem cell bill."
Not to be outdone in the effort to put a sympathetic face to the cause, Brownback appeared at a news conference with children born from fertility clinic embryos.
"Embryos are human," said Steve Johnson, who appeared with his wife and their 4-year-old daughter, who began as a frozen embryo they "adopted." "They need to be given a chance to live."
The debate has put senators in an unaccustomed position of bandying medical jargon and quoting from arcane science journals. But the debate also involves a powerful personal dimension, because many senators -- like many Americans -- have ailing relatives who might be helped by scientific advances.
Sen. Dianne Feinstein (D-Calif.), for example, told of a 44-year-old relative with Parkinson's disease. Sen. Byron L. Dorgan (D-N.D.) recalled his daughter's death from heart disease.
The issue also is a politically tricky one for some Republicans who worry that their opposition to embryonic stem cell research, applauded by conservatives, may be viewed by others as an obstacle to scientific progress.
To blunt that impression, GOP leaders have arranged to send to Bush two uncontroversial research bills that he is to sign when vetoing the broader bill. One is designed to encourage alternative methods of deriving stem cells, without destroying embryos. The other would address fears of some critics that scientists are aiming to create "fetus farms," in which fetuses would be grown for their organs and tissues.
Both bills are expected to pass the House and Senate today.
But the central debate is over the cutting-edge research that involves destroying human embryos to obtain stem cells, which are thought to be able to develop into any type of cell in the body. Many scientists believe such research may lead to cures or treatments for now incurable ailments.
Under current law, scientists can use federal money for such research only with lines of stem cells created before August 2001, when Bush laid out his policy. Scientists are pushing to lift that restriction, in part because the stem cell lines available under that policy have proved limited.
Officials at the National Institutes of Health say that of the 78 stem cell lines that were expected to work, about 20 have proved useful in research. And because many of those are deteriorating or are unsuitable for human use, most of the research is limited to about six lines, NIH officials say.
"These policies are making scientists work with one arm tied behind their back," said Sen. Tom Harkin (D-Iowa). "The president's policy is not a way forward. It is a dead-end street."
The bill before the Senate would overturn Bush's 2001 policy by allowing federal funding for research on a broad new category of stem cell lines: those derived from frozen embryos held at fertility clinics and scheduled for destruction.
Proponents say the measure is ethically sound because the embryos in question would be destroyed anyway.
But critics say it is still immoral.
"Just because the budding life will not survive does not mean that we should ghoulishly conduct experiments on them," said Sen. Jim Bunning (R-Ky.).
Brownback argued that a better fate for excess fertility clinic embryos would be to allow childless couples to adopt them for their own pregnancies.
About 138 people have done so since 2002, according to Specter.