But members of Congress were told Wednesday that legislation won't stop science.
The issue is not so much on cloning to make people — there is a broad consensus against that — but whether to also ban the use of embryonic cloning technology to search for cures to diseases. There is tremendous disagreement over that.
Senate Majority Leader Tom Daschle said the Senate had spent more time than he had anticipated on energy and trade legislation, leaving too little time to bring up cloning legislation before the Memorial Day congressional recess.
The fate of the legislation is uncertain, with some senators still undecided or at least unannounced.
"I think we're probably going to have to pick up where we left on stem cell research sometime after we get back," Daschle, a South Dakota Democrat, told reporters.
"Humans will be cloned," Dr. Panos Zavos of the Andrology Institute of America told a House hearing Wednesday, likely this year, and there is nothing Congress can do to stop it.
"This is not the time to panic and try to turn back the clock," he added. "The genie is already out of the bottle."
But not yet. Zavos told Congress he doubts the claims of an Italian doctor who says he has already impregnated women with cloned babies.
"I don't believe those reports," he said. "I may have been born elsewhere, outside the U.S., but I am still from Missouri."
Mainstream medical groups say cloning is not safe nor wise, and Florida Republican Dave Weldon, also a doctor, added "not moral."
"No one has the right to create children to their own specifications," he told colleagues.
However, several doctors warned the panel the House bill that bans all cloning research goes too far and could prevent doctors from finding cures for many devastating diseases.
While lawmakers across the political spectrum are strongly opposed to "reproductive cloning" — an attempt to create a cloned human baby — there is division about whether "therapeutic cloning" should be allowed.
Under therapeutic cloning, an embryo is created and stem cells — primitive cells that have the ability to transform into many other cell types — extracted for medical research. The embryo is destroyed and is not implanted in a woman's uterus to become a baby.
The debate is being heavily lobbied and is the source of a number of emotional advertising campaigns. The issue is expected to play a role in campaigns in states with close votes in this congressional election year.
The House of Representatives last year passed a bill, strongly backed by President Bush and anti-abortion rights groups, that would ban all types of human cloning. Similar legislation has been introduced in the Senate by Kansas Republican Sen. Sam Brownback and Louisiana Democratic Sen. Mary Landrieu. Debate has been put off several times.
Competing legislation sponsored by Democratic Sens. Edward Kennedy of Massachusetts, Tom Harkin of Iowa and Dianne Feinstein of California and Republican Sen. Arlen Specter of Pennsylvania would outlaw any attempt to clone an actual human being, but would allow therapeutic cloning.
Foes of cloning say it is immoral to create an embryo only to destroy it, and say it could lead to a society in which, as Bush put it in a speech last month, "human beings are grown for spare body parts and children are engineered to custom specifications."
But advocates of therapeutic cloning say it is a promising avenue of stem cell research that could lead to treatments for a wide range of diseases, including Parkinson's, Alzheimer's, diabetes and cancer.