Severino Antinori, the Italian fertility specialist notorious for helping a 62-year-old woman have a baby after in vitro fertilisation, sparked controversy again yesterday when he reiterated that he would move ahead quickly to clone a human being.

Antinori was speaking at the US National Academy of Sciences in Washington DC. The usually sedate surroundings, characterised by a thoughtful Albert Einstein outside the Academy's marble facade, were transformed into something of a circus, with TV cameras pursuing Antinori wherever he went.

Coming a little over a week after the US House of Representatives voted 265 to 162 to ban all cloning research — both for reproductive and therapeutic purposes — Antinori's claims will do little to soften political attitudes when the Senate considers the legislation.

The House vote came after lawmakers had also rejected a less restrictive measure that would have prohibited reproductive cloning, while leaving open the door for therapeutic cloning (in therapeutic cloning, the embryo never develops beyond a few days, but has the potential to enable development of tissues to replace diseased or damaged tissue). Carl Feldman, president of the Biotechnology Industry Organization, called the ban, "a step backwards. Potentially millions of patients affected with Alzheimer's, diabetes, Parkinson's, heart disease, and various cancers will be affected."

Feldman and others now look to the Senate for support of therapeutic cloning, but the leadership is still undecided about the merits and demerits of the research. Speaking immediately after the House vote, Senate Majority Leader, Tom Daschle (Dem, South Dakota), said he was opposed to reproductive cloning and "very uncomfortable with even cloning for research purposes." Confusingly, he added that he strongly supports efforts to try to advance science and research through the use of the embryo. He has yet to make a final decision about his views.

Senator Edward Kennedy (Dem, Massachusetts), chairman of the Senate Health, Education, Labour and Pensions Committee, was more definitive, saying he opposed a ban on cloning for research. "The Senate rejected similar legislation in 1998, and it should do so again."

While Congress continues the political debate, scientists are doing their best to keep therapeutic cloning research alive by exploiting the wording of the bill, which bans only cloning using cells with two sets of 23 chromosomes, the normal number. But Peter Mombaerts, a scientist at Rockefeller University in New York, says cloning can also be done with cells that are in the midst of dividing, when they have twice the normal number of chromosomes, or with sperm and eggs cells that have half the usual complement of DNA.

It seems likely, though, that Antinori's announcement yesterday raises the game, and if his team does go ahead, politicians are unlikely to leave such a loophole for long.

To complicate matters further, the cloning debate is entangled with the ethical and political issues of embryonic stem cell research. These cells have the potential to become anything from brain to skin, and the hope is that science will eventually find a way to coax them to create replacement cells for damaged or diseased tissue.

Currently, researchers work with cells from embryos discarded after in vitro fertilisation. If science ever succeeds in routinely commanding embryonic stem cells to become a particular tissue type, strong immuno-suppressant drugs will be needed to overcome rejection of the tissue such cells generate. But if an embryo can be created from an enucleated donor egg and genetic material from an individual's own cells (therapeutic cloning), the tissues generated by the stem cells would be largely compatible with the patient's immune system.

Many who support embryonic stem cell research on discarded embryos are uncomfortable with the idea of creating embryos specifically for their stem cells. Others, such as Rep Anna Eshoo (Dem, California) argue that without therapeutic cloning, "there's no way to move stem cell research from the lab to the doctor's office. It's unconscionable for us not to continue to be the merchants of hope."

Michael West, chief executive of Advanced Cell Technology, a private company that is developing human cloning for research, not reproductive, purposes, says, "If people understood the facts, there would be a consensus, as there is in the scientific community, that these technologies have great merit."

John Gearhart, a Johns Hopkins University professor who three years ago pioneered the isolation of human embryonic stem cells, said the anti-cloning legislation would be a "serious setback" for American science.

"The likelihood is that the most cutting-edge research would move to the United Kingdom (where legislators approved therapeutic cloning after a debate in the House of Commons very similar to that in the House of Representatives) and other countries that allow it to go forward," said Gearhart, expressing a view that was shared with most of the leading researchers in this burgeoning field.

"This legislation would force scientists to leave the United States and go to other countries like the United Kingdom because it carries prison sentences and severe fines that will not be taken lightly," said David Humpherys, a molecular biologist at the Whitehead Institute in Cambridge, Massachusetts.