The resounding victory of California's $3 billion ballot initiative for embryonic stem cell studies may have the unintended consequence of slowing research on the national level and creating a backlash from religious conservatives who feel emboldened by President Bush's reelection, say activists on both sides of the issue.

With the support of Republican Gov. Arnold Schwarzenegger, Californians approved the bond proposal 59 percent to 41 percent, paving the way for a 10-year project that aims to make the state a global leader in the controversial new field.

Already, the initiative is upending the biomedical industry, prompting some entrepreneurial scientists to relocate from other states and several California universities to draw up blueprints for new laboratories. But the measure has reinvigorated a battle in Washington over the government's role in science, the meaning of this year's election results and the question of when life begins.

"California putting such an extravagant amount of money into embryonic stem cells and cloning research really takes the wind out of the argument there needs to be federal funding," said Wendy Wright, senior policy director of Concerned Women for America, a conservative advocacy group that opposes the research. "Moral values was a strong premise for many people's vote, and that should give congressmen pause to look at the public policies they're backing and assess them against moral values."

In the Senate, where Republicans picked up four seats, Sen. Sam Brownback (R-Kan.) is considering expanding his legislation banning human cloning to include a prohibition on research that mixes genetic material from humans and animals. The bill as currently written outlaws a laboratory process in which cloned embryos are made in a petri dish. Scientists say the process, called somatic cell nuclear transfer (or therapeutic cloning), is a great potential source of embryonic stem cells.

"It seems that most of the country agrees with John Kerry that life begins at conception," Brownback said in an interview. "If that's the vast middle swath of the country, then it seems we should be able to move something like this through." And as they have on issues such as gun control and same-sex marriage, he thinks Democrats may retreat from the most liberal positions related to stem cell science, such as allowing therapeutic cloning.

One vote-counting stem cell advocate said proponents lost at least three prominent backers in the Senate. The source, who feared retribution if named, expects Bush to "cater" to the religious right. "They put him in office." He fears the California program "will be a big excuse for the president to not even have to deal with this."

Under Proposition 71, California researchers are eligible for $295 million a year in grants to work on cell colonies -- or lines -- taken from five-day-old human embryos. Scientists say embryonic stem cells hold great promise for treating conditions such as juvenile diabetes, Parkinson's disease and spinal cord injuries, because the cells can morph into virtually any type of tissue or cell.

Opponents say the work is akin to murder because extracting the stem cells kills the embryo. In August 2001, Bush struck a compromise, announcing he would allow federal funding for research on the limited number of cell lines that existed then. Researchers and patient groups have been frustrated by those restrictions, saying the 20-plus available lines and $24 million in federal grants have not been sufficient.

Led by a real estate developer whose son has Type 1 diabetes, an eclectic coalition of patients, Hollywood celebrities, Nobel Prize winners and venture capitalists bankrolled the California initiative, raising almost as much money as the total federal investment in embryonic stem cell research.

In Massachusetts, Robert Lanza, medical director of Advanced Cell Technology, said the measure will "usher in a new era" of medical breakthroughs that will benefit not only Californians "but all Americans." The company, which conducted some of the earliest efforts to retrieve stem cells from normal and cloned human embryos, has sent its CEO to the West Coast to scout possible laboratory sites.

Much of the debate over the broader implications of Proposition 71 stems from two dramatically different interpretations of this year's election results.

Pointing to national surveys that registered 70 percent support for stem cell research and the fact that Proposition 71 drew almost 300,000 more votes in California than Democratic nominee Kerry, advocates say the president's policy is out of step with most Americans, including many Republicans.

"People in the Bush administration know what worked for them this year and what didn't," said Daniel Perry, head of the Coalition for the Advancement of Medical Research, which promotes stem cell science. "They understand stem cell research was appealing to people at a very profound and fundamental level -- the level of hope."

Rep. Michael N. Castle (Del.), president of the Republican Main Street Partnership, said the overwhelming victory in "the most significant state in the country, with a Republican governor endorsing it, is very hard to ignore." He said 190 House members have endorsed his bill expanding federal funding to research on stem cells obtained from "spare" embryos at fertility clinics, if donors give written consent and do not receive a financial inducement.

Last summer, Senate Majority Leader Bill Frist (R-Tenn.), a physician, said he thought the Bush policy should be revisited after Election Day. The implication, according to Castle and others, was that Frist hoped to broaden it. Now Frist is not certain that would be possible in the new, more Republican Senate, said one adviser who could not be quoted discussing internal deliberations.

"The fulcrum of the center has moved to the right," this aide said, making it hard "for people who want to expand the president's policy."

Weighing on Frist is the potency of the stem cell issue with the GOP base, his adviser said. "We've been surprised by the fervor. It almost rivals abortion."

Many conservatives argue that California does not represent mainstream America and that the authors of Prop 71 overstepped by allowing state funding of therapeutic cloning.

"This means California will become a center for human cloning research, and I don't think most voters realized that," said Richard M. Doerflinger, deputy director for pro-life activities at the U.S. Conference of Catholic Bishops.

"It will invite retaliatory action by people like Senator Brownback, who wanted to criminalize all types of research," said H. Rex Greene, a San Mateo physician who opposed Prop 71. "That's what these guys invited when they took such an extreme position." Brownback's cloning ban would make it a crime for patients treated outside the United States with therapies derived from embryonic stem cells to reenter.

Doerflinger said the bishops' conference may revive its campaign to pressure undecided lawmakers to support the Brownback bill, which he said may have a majority of Senate votes but perhaps not a filibuster-proof 60 votes.

At a minimum, conservatives expressed confidence they will be able to curtail federal spending on embryonic stem cells by arguing that at a time of growing deficits it is unnecessary to duplicate California's massive investment.

Carl Feldbaum, president of the pro-research Biotechnology Industry Organization, said he does not expect the political wars to cease until there is a "demonstrable success" in the laboratory. "People are claiming it's unproven and may not work," he said. "The research will have to debunk that."