"All indications are 2002 could be the year of the clones," the scientist, Dr. Panayiotis Zavos, who runs a fertility clinic in Kentucky, told a House subcommittee this afternoon at a hearing that was apparently timed to sway the Senate debate. But Dr. Zavos, who has made such statements before, said he had not created a cloned human embryo, which is the first step toward cloning a baby.

The House has passed legislation that would ban human cloning for reproductive or medical research, and President Bush is urging the Senate to do the same. Senator Tom Daschle, Democrat of South Dakota, the majority leader, had promised a vote before the Memorial Day recess, but the debate has been delayed until June at the earliest.

At today's hearing, House Republicans said they hoped the Senate would follow their lead. "The Senate needs to stop delaying," said Representative Dave Weldon, Republican of Florida, who led the effort to ban cloning in the House. He called human cloning "a threat to society."

Agreement among lawmakers is widespread that reproductive cloning — making babies that are genetic replicas of adults — should be outlawed. At issue in the Senate is whether to enact a far-reaching ban, as the House did, or to prohibit reproductive cloning but keep the door open for research on cloned human embryos.

Lawmakers on both sides say the debate is too close to call.

Proponents of research cloning said it could benefit millions of patients. But opponents argue that once embryos are cloned, it will be impossible to stop scientists from using them to impregnate women — an argument that a Justice Department official endorsed in a statement Mr. Weldon released today.

Fertility clinics routinely transfer embryos from the laboratory to women's wombs, wrote the official, Daniel J. Bryant, an assistant attorney general in the department's office of legislative affairs. Mr. Bryant said it would be impossible for the authorities to distinguish between ordinary embryos and cloned ones.

"Entrusted with enforcing such a limited ban," Mr. Bryant wrote, "law enforcement would be in the unenviable position of having to impose new and unprecedented scrutiny over doctors in fertility clinics."

In his testimony, Dr. Zavos warned that human cloning would go on, if not in the United States, then elsewhere. But he said he had no intention of trying cloning in this country. At a news conference outside the hearing room, Dr. Zavos said he had set up two laboratories overseas, one in, "I guess you could say it's Europe" and the other in "territory between Greece and India."

Despite criticism from prominent scientists who say human cloning would result in deformed babies, Dr. Zavos said he has lined up 12 infertile couples from around the world, including some from the United States, who want to conceive by cloning.

But with other nations also restricting cloning experiments, he has had to move slowly, he said, "tiptoeing through the tulips where all these countries and governments are throwing spitballs at you."