In a draft report circulated last week, scientists from the US National Institutes for Health made an impassioned case for the funding of stem-cell research.
The potential of such research, using material harvested from human embryos created in test tubes, they argued, is to make possible breakthroughs in such diseases as Alzheimer's, Parkinson's and diabetes. Literally tens, possibly hundreds, of millions of people could benefit.
In doing so they have joined other scientists and politicians in an ethical debate that is dividing the US administration and may yet set it on a confrontation course with a key part of its constituency, the anti-abortion lobby, and a key target constituency, Catholic America.
President Bush is due to decide shortly whether to reverse a ban instigated by him on federal funding of the research in the first days of his administration to prove his "pro-life" credentials.
And he is coming under pressure to do so from influential Republicans, not least his Health Secretary, Mr Tommy Thompson, a Catholic anti-abortionist, and prominent Republican members of the Senate.
One of the country's most respected anti-abortionists, Utah's Mormon senator, Mr Orrin Hatch, has become one of the most determined advocates of stem-cell research. "Stem-cell research facilitates life. Abortion destroys life," he said.
He is joined by such other senators as the Florida Republican Connie Mack and North Carolina's Strom Thurmond, and 38 Republican members of the House. "I am just as pro-life today as I was before I had had any knowledge of stem cells," says Mr Mack.
At stake is the ability of scientists to grow cultures of healthy cells from microscopic cells extracted from newly formed embryos, and now, but with less success, from adult humans. The embryos used are not developed foetuses at this stage, but a collection of differentiated cells, and come from those created in abundance in test-tubes in fertility clinics to help childless couples. The bulk of such embryos are routinely discarded.
Proponents of the research say that to give such "potential life" the same status and protection as anti-abortionists claim for a foetus in the womb would in effect be to describe such fertility treatment, with its inevitable discards, as akin to mass murder. That is a proposition which polls show is simply not accepted by the majority of Americans who back stem-cell research.
What Mr Bush is being asked to reinstate is not a carte blanche for researchers. A Clinton administration compromise regulation required that federally-funded researchers were not allowed to destroy embryos for the purpose of stem-cell research, they were obliged to use only cells which had been extracted by others from embryos that were being discarded. Payment for embryos or their production simply for research is ruled out.
Speaking during the election campaign Mr Bush specifically opposed "research that involves destroying living human embryos", but some see the statement as carefully calibrated to allow him to stand over the Clinton position.
For the Catholic Church, however, such distinctions do not change the fundamental nature of the act.
"The idea that someone may otherwise be discarding the embryo anyway is not relevant for our government," Mr Richard Doerfinger, an official of the National Conference of Catholic Bishops, told the Washington Post. "Destroying an embryo in the lab is morally the same as abortion in Catholic teaching," he insisted.
That view is shared by the majority of the anti-abortion movement, despite distinguished defections on the issue by such as Mr Hatch, and voices close to the president, notably his chief political adviser, Mr Karl Rove, are believed to fear that important voter groups may be alienated if Mr Bush retreats.
