The US Senate on Tuesday strongly backed bipartisan legislation to expand federally funded embryonic stem cell research, but President George W Bush has vowed to veto the measure as morally indefensible.
The vote was 63-37, four short of the 67 that would be needed to overturn the veto that could come on Wednesday. All but one Democrat voted for the bill, while 19 Republicans backed it and 36 opposed it.
The House of Representatives has approved the bill but supporters there do not expect to have the two-thirds needed to override a veto either.
White House spokesman Tony Snow said the veto, Bush's first, would be "pretty swift."
"He is fulfilling a promise that he has long made and he is keeping it," Snow said.
The Senate also passed unanimously two related -- but less controversial -- bills which Bush planned to sign. The House quickly passed one of them, to block "foetus farming," or implanting a human embryo in a woman or animal for the purpose of harvesting cells or tissue.
But House Democrats blocked the second one which would promote research to obtain stem cells without destroying an embryo. That research is already being done and some Democrats said the legislation was merely political cover for Republicans who oppose the more far-reaching embryonic stem cell bill.
Embryonic stem cell research has been the centre of an ethical and political maelstrom and has become an issue in several of this November's congressional races.
Advocates and scientists cite the immense promise that stem cells, identified less than a decade ago, hold for people with diabetes, spinal cord injuries, Parkinson's and other illnesses.
STRONG PUBLIC SUPPORT
Opinion polls show strong public support for expanding federally backed embryonic stem cell research and disease advocacy groups have lobbied for it. Nancy Reagan, widow of former President Ronald Reagan who died of Alzheimer's, has sought support from fellow Republicans.
But Bush says it is unacceptable because extracting the stem cells, which have the potential to become any kind of organ or tissue cells, means the days-old embryo is destroyed.
"This is about the value of human life," said Pennsylvania Republican Sen. Rick Santorum, a strong foe of the research who is in a tight election race. "It's very easy -- that little embryo doesn't have a pair of eyes, a hair colour, it doesn't have a name. It's very easy to dismiss this entity as insignificant."
Supporters, led by Pennsylvania Republican Sen. Arlen Specter and Iowa Democratic Sen. Tom Harkin, pointed out that the bill would permit research only on leftover embryos from fertility treatment that would otherwise be discarded.
"These embryos are never going to be babies," said California Democratic Sen. Dianne Feinstein. "Think of the lives the embryos might save someday. People paralyzed. Juvenile diabetes. Young people with Parkinson's disease who can't move, who have trouble speaking."
In 2001, Bush allowed federal funding on 78 stem cell lines then in existence, but most of those turned out to be of limited use to scientists who have pressed Congress to expand federally funded research.
"This is what our leading scientists have told us they want and need to move the field of stem cell research forward," said Utah Republican Sen. Orrin Hatch, who like Bush opposes abortion rights but broke with the president on this issue.
With Republicans divided, stem cell research has become an issue in some congressional races this year and may play a role in the 2008 presidential contest.
Of the five Republican senators considering seeking the presidential nomination in 2008, three -- George Allen of Virginia, Sam Brownback of Kansas and Chuck Hagel of Nebraska -- voted against it. Two, John McCain of Arizona and Senate Majority Leader Bill Frist of Tennessee, broke with Bush and supported expanding the research.