President Bush was speaking directly to doctors, scientists, religious activists and disabled people last week when he urged a broad ban on cloning. Indirectly, he was trying to pressure the Senate to follow the House in supporting his ban. The Senate should consider doing so – but only if the president extends his ban to a major source of the supply of research embryos, in vitro fertilization.

The president pointed out last week that the majority of Americans supported his call for a ban, but that may be because he stays away from the process that allows many couples who would like to have children but can’t a second chance, thanks to scientific advancements of a generation ago. In vitro fertilization introduces egg and sperm outside a woman’s body, implants one or a few of the successful result and eventually either dumps the rest or passes them along for stem-cell research.

The use of IVF embryos, like those produced from cloning, show promise in producing insulin-secreting cells for diabetes; nerve cells in stroke or Parkinson’s disease; or cells to repair a damaged liver and treatment for other degenerative diseases. Therapeutic cloning removes the DNA from an embryo and replaces it with the DNA from a cell removed from an individual. The resulting embryo is allowed to grow for a couple of weeks, after which the stem cells are extracted and encouraged to grow into healthy tissue to replace the individual’s degenerating tissue. But the embryo, as with the excess IVF embryos, is destroyed.

President Bush wants the research ban on cloning because “Life is creation, not a commodity.” “Advances in new biotechnology must never come at the expense of human conscience,” he said. “As we seek what is possible, we must always ask what is right, and we must not forget that even the most noble ends do not justify any means.”

The president is pretending that banning this research will prevent science from destroying embryos. This is untrue, although adding it to a ban on IVF, which may not yield the same level of public support as the research ban, would help that result along significantly. But he does not call for the IVF ban – and has, in fact, supported the use of IVF for couples trying to conceive – because this is not a debate over whether an eight-celled blastula is entitled to the full range of human and constitutional rights. He also pretends that there is a moral difference between using leftover IVF embryos and creating embryos specifically for therapeutic research, but one is not more or less a commodity than the other.

The Senate has two bills on cloning before it: one the president supports that bans all types of cloning; and one that allows for therapeutic cloning but bans cloning strictly to produce babies. Sens. Olympia Snowe and Susan Collins, properly, support the latter, as do 40 Nobel laureates who recently signed a letter saying a medical-research ban would be a mistake.

The cloning issue lends itself to political mischief because it is complicated, but the question underlying the debate is fairly simple: What potentially is gained by banning this medical research and what is lost?