A move to expand federal funding for embryonic stem cell research has the backing of the U.S. House and next week likely will see passage in the Senate.

But that's where the effort likely dies. President Bush has once vetoed legislation to expand that type of stem cell research and has threatened to do so again.

"We're certainly not going to win it this year, but that doesn't mean you stop fighting for it," acknowledges one of the effort's chief supporters, Utah Sen. Orrin Hatch, who as a conservative Republican has rallied support among his colleagues hesitant to boost the research.

Cells cultivated from human embryos hold the most promise for scientific research because they can be transformed into any type of cell in the body, supporters of the research say. Opponents, however, argue that the research destroys the embryo and therefore, human life.

Congress has debated repealing Bush's limits on federal funding for embryonic stem cell research before, culminating last year in the president's first veto. This year, supporters are muscling grass-roots support and lobbying hard to get a veto-proof majority in the Senate. Some say they have 66 votes, leaving them needing one more to overturn Bush's expected veto.

"Even though it's possible to get to veto override in the Senate, it will be tough," says John Hlinko, founder of the advocacy group StemPAC. "Getting to one in the House is much more difficult. The odds of it passing are slim."

Reviving the debate when even supporters acknowledge they will fail still matters, they say, because it again raises the issue with the public and puts Bush in a tough position to use his veto on a measure many see as a potential life-saver.

"The help offered by stem cell research is too great to ignore," Hatch says. "I think the president is on the wrong side of history here. His advisers put him on the wrong side of history."

Even Bush's own top scientific adviser disagrees with his position.

In 2001, Bush was the first president to allow federal funding to go to research on 68 currently existing stem cell lines, but he also capped the money only for those lines. Scientists now say that policy is blocking trailblazing discoveries because most of those lines are tainted and are unusable.

Elias Zerhouni, director of the National Institutes of Health, told a congressional subcommittee recently that he believes the president's executive order against further research needs to be rescinded.

"Since 2004, I think it's very clear from the point of view of science and what I have overseen, that these cell lines will not be sufficient to do all the research we need to do," Zerhouni testified. "So from my standpoint, it is clear today that American science would be better served and the nation would be better served if we let our scientists have access to more cell lines."

The Bush administration disagrees.

In a statement of administration policy, Bush's advisers say the bill would use federal "taxpayer dollars to support and encourage the destruction of human life for research."

"Destroying nascent human life for research raises serious ethical problems, and millions of Americans consider the practice immoral," the policy statement says.

Sen. Sam Brownback, a Kansas Republican and contender for the GOP presidential nomination, is one of the staunchest opponents of expanding embryonic stem cell research with federal funds. He backs other adult stem cell research, such as those taken from umbilical cord blood, and is pushing a measure to ban human cloning.

"Embryonic stem cell research is unethical and has yet to deliver treatments or applications," the senator said in a statement. "Eventually, I hope the Senate will vote on my bill to ban human cloning, but for now I welcome the opportunity for a full and open debate on whether we should use taxpayer dollars for research that is both unethical and without a track record of real results."

After the debate, though, it's clear the bill won't make it far this year.

Hatch says that's OK. Asked why supporters are still pushing a measure they know will be swiftly tossed out by the White House, Hatch said it's an easy answer.

"Great battles don't always occur overnight," Hatch said.

tburr@sltrib.com