WASHINGTON -- President Bush pressed the Senate on Wednesday to ban cloning of human embryos for research, saying science must not rush ahead "without an ethical compass." Senators promised a fight, seeing great promise in cloning for cures of terrible afflictions.

Bush called medical researchers, ethicists, lawmakers, ministers and disabled people to the White House to explain why he objects to human cloning and to embrace a ban proposed by Sens. Sam Brownback and Mary Landrieu.

"We can pursue medical research with a clear sense of moral purpose, or we can travel without an ethical compass into a world we could live to regret," Bush said. "How we answer the question of human cloning will place us on one path or the other."

The president was looking to tamp down an evolving Senate compromise, crafted by Sens. Arlen Specter, Edward Kennedy, Tom Harkin and Dianne Feinstein, that would outlaw cloning for reproductive purposes but allow it for research on illnesses such as cancer, Alzheimer's and Parkinson's.

"It would be a mistake for the U.S. Senate to allow any kind of human cloning to come out of that chamber," Bush said.

Kennedy, D-Mass., said it is Bush who is mistaken.

"We must not let the misplaced fears of today deny patients the cures of tomorrow," he said. "Congress was right to place medicine over ideology in the past, and we should do the same again as we confront the issue of cloning."

Specter, R-Pa., said the ban Bush advocates would criminalize legitimate research and cause "an enormous brain drain out of the United States to Europe."

Opposition forming

"To tie the hands of medical science in the 21st century, in my opinion, is just not the right thing to do," Specter said.

"There's going to be a real fight on the Senate floor. I believe we will find enough Republican votes ... to make a majority."

Senate Majority Leader Tom Daschle, D-S.D., urged lawmakers to heed a call from 40 Nobel laureates who support research cloning, and he said it is possible to bar ethically repugnant uses of cloned tissue without blocking the research.

"The president wants to ban it all, and I think he's wrong," Daschle said.

"And I think the American people are on our side on this issue."

At issue is the production of embryos that are genetically identical to a donor human being. Bush voiced his opposition frequently last year, and in August he restricted federally financed stem cell research to 64 existing stem cell lines taken from embryos discarded by fertility clinics.

The House passed a ban on all human cloning last July but the Senate has not acted on it.