President Bush vowed Friday to use the first veto of his presidency to stop Congress from expanding government-funded embryonic stem cell research, pledging to uphold a line he had already drawn against science that “destroys life in order to save life.”

The president’s threat aimed to stop the momentum of a measure that could pass the Republican-led House as early as Tuesday and has broad support in the Senate.

The statement reflected White House concern that the president was being thrust into a dispute that pits the bulk of public opinion, which is moving increasingly in favor of expanding such research, against the views of Bush’s socially conservative base, which believes the research is immoral because embryos are destroyed.

“I made it very clear to the Congress that the use of federal money, taxpayers’ money, to promote science which destroys life in order to save life -- I’m against that,” Bush told reporters in the Oval Office. “And therefore, if the bill does that, I will veto it.”


Stem cells taken from embryos have drawn broad interest because they are thought to be able to grow into any type of cell in the body. Researchers hope to learn how to grow them into replacements for the cells or tissues that are faulty in juvenile diabetes, Parkinson’s disease and other ailments.

Bush also criticized a research development in South Korea, announced Thursday, in which scientists produced embryonic clones of 11 patients and then extracted stem cells from the embryos. The researchers said the embryos did not have the ability to develop into babies and were produced only to harvest stem cells after five days.

Through cloning, they aimed to produce cells that were a genetic match for the patients, reducing the risk of tissue rejection or other complications.

Nonetheless, the South Korean development reignited the debate over the use of cloning in stem cell research. One concern is that further development of cloning technology could lead to the ability to produce cloned children.


“I’m very concerned about cloning,” Bush said. “I worry about a world in which cloning becomes acceptable.”

Friday’s events underscored the politically challenging nature of an issue that has simmered since Bush’s first months in office, when he struggled to reconcile the needs of patients seeking cures with ethics concerns about destroying human embryos.

The president appeared to think he had found a middle ground. In August 2001, he authorized the first federal funding for research using human embryonic stem cells but limited that funding to cell lines that were already in existence. The policy, he said, was meant to allow research to move forward without causing additional human embryos to be destroyed.

His policy, however, faced growing criticism when it was learned that far fewer lines qualified under the restrictions than the president had said, and some of those that did qualify turned out to be of limited use.


In California, an initiative to spend $3 billion on embryonic stem cell research -- which was planned not long after Bush announced his restrictions on federal funding -- was approved in November with 59% of the vote. Dissent against Bush’s policy has grown in other states, including Wisconsin, New Jersey, New York, Massachusetts and Illinois, where officials have proposed state money or policy shifts to promote the research.

The House legislation would allow the government to pay for research using stem cells taken from embryos at any date, not just stem cells created before August 2001.

Under the legislation, the stem cells would have to come from embryos created by couples at fertility clinics that the couples do not plan to use. The bill does not authorize federal funding for experiments that create embryos through cloning or other means.

No federal law bars scientists from using private funds to create embryonic stem cells for research.


The chief sponsor of the House measure is Rep. Michael N. Castle (R-Del.), the head of a group of moderates known as the Republican Main Street Partnership. More than two dozen Republicans are cosponsoring the bill, along with more than 170 Democrats.

Tensions within the Republican Party over the Castle bill erupted last week when House Speaker J. Dennis Hastert (R-Ill.) told his caucus that he intended to make good on a promise to moderates to allow a vote on the measure before June, and that he would probably bring the bill to the floor next week.

Conservatives angrily objected, participants said, arguing that no Republican-controlled Congress should overturn a Republican president’s policy on an issue considered fundamental to the party.

“I was disappointed by the decision,” said Rep. Mike Pence (R-Ind.), head of the conservative Republican Policy Committee. “A large number of conservative members were disappointed that this bill was scheduled for a vote.”


In opposing expanded research on embryonic stem cells, Bush and other conservatives are fighting a growing tide of public opinion, recent surveys show.

In a Gallup poll this month, 60% of people surveyed considered research using stem cells obtained from human embryos to be “morally acceptable.”

A December survey by the nonpartisan Pew Research Center for the People and the Press showed that even the Republican Party’s core was divided. In that poll, 40% of self-described social conservatives said that conducting stem cell research aimed at new cures was “more important” than not destroying the “potential life of human embryos.” Some 45% of conservatives said it was more important to spare the embryos.

Andrew Kohut, director of the Pew center, said the support for stem cell research had been steadily increasing since 2002, the first time the center asked the question.


The growing support, he said, “shows that there are some political risks, no question about it,” for Bush if he vetoes a bill that would expand federal funding for the research. “There is risk in how people in the middle of the political spectrum feel about him and the party,” Kohut said.

Expanding embryonic stem cell research has drawn support even from some prominent abortion opponents, including Sen. Orrin G. Hatch (R-Utah), who is sponsoring legislation to ease federal restrictions. Former First Lady Nancy Reagan began speaking out in favor of embryonic stem cell research after her husband developed Alzheimer’s disease.

“I think this is the most pro-life thing you could do,” said Rep. Joe Schwarz (R-Mich.), a freshman congressman and physician who backs the legislation and who describes himself as a Catholic and an abortion foe.

Hatch, who calls himself a “strongly pro-life senator,” said after Bush’s veto threat: “I do not believe that life begins in a Petri dish and, like many others, hope that these excess embryos can benefit mankind.... For me, being pro-life means helping the living.”


Underscoring the popularity of stem cell experiments, Hastert plans to allow a vote next week on a measure that would encourage research on a type of stem cell drawn from umbilical cord blood. Conservatives view the bill as an alternative to the Castle legislation.

Kohut said a Bush veto of expanded embryonic stem cell funding would probably remind Americans of the move by Congress this year to intervene in the case of Terri Schiavo, a brain-damaged Florida woman.

“There is a risk, again, of Republicans becoming positioned as the party of the religious right and not the moderates. That is a big risk,” Kohut said.

Conservatives acknowledged this week that they did not want Bush in the position of vetoing the stem cell legislation.


“It does not look good for his first veto,” said Jessica Echard, executive director of the conservative Eagle Forum, which is lobbying lawmakers to oppose the legislation.

One leading conservative lawmaker, Sen. Sam Brownback (R-Kan.), said he would filibuster the measure to prevent it from reaching Bush’s desk.

“I think he [Bush] would look and say that any bill that comes up from a Republican House and Senate that he has to veto is a difficult issue,” Brownback said. “In a Republican House and a Republican Senate, we ought to be able to avoid it.”

Times staff writer Megan Garvey in Los Angeles contributed to this report.