In a challenge to President Bush, the House of Representatives has approved legislation by a vote 238 to 194 to expand federal government funding for research using embryonic stem cells. House action came just days after a new advance in stem cell research in South Korea, which many lawmakers say underscores the need to intensify stem cell research in the United States.

Stem cell research is among the most difficult issues debated by Congress, triggering strong emotions on both sides of the political aisle.

Proponents of expanding federally funded research involving additional human stem cell lines say lowering barriers to wider studies would help find cures to such diseases as Alzheimer's, Parkinson's, cancer, and others.

Opponents frame arguments along moral lines, saying those seeking government money to use embryonic stem cells for research are asking millions of taxpayers to support something they find morally objectionable. They also say research on the promise of embryonic cells has been exaggerated.

Of two bills at issue in Tuesday's debate, one would allow researchers access to more stem cell lines by using surplus embryos from In-Vitro Fertilization clinics used with permission of donors.

Delaware Republican Michael Castle spoke in favor of his legislation, which, if approved by Congress, would lift President Bush's ban on new federally funded research requiring the destruction of human embryos. "This is not the time to allow bad science, or ideology to get in the way of doing what is right for the people of this country and of the world. There are 110-million people in the United States of America who potentially could be helped by embryonic stem cell research," he said.

Mr. Castle had support from many moderate House Republicans, reflecting the split in the majority party and differences with President Bush over the issue.

Indiana's Mike Pence reiterates his strong opposition to using government money to expand research. "I believe it is morally wrong to destroy human embryos for the purposes of research, but I believe it is doubly morally wrong to force millions of pro-life Americans to see their tax dollars used to support research that they find morally offensive," he said.

Supporters of the legislation, such as Democrat Jim Cooper, pointed to the recent advance reported by South Korean researchers, saying the United States is falling behind. "This research needs to be conducted, it needs to be conducted with federal support, it needs to be conducted here in America. There was a breakthrough just last week in South Korea. Are we going to send our loved ones overseas in order to get this life-saving research. We need to do it here," he said.

President Bush directed in 2001 that government-supported stem cell research should be limited to 78 stem cell lines, a restriction many lawmakers believe should be maintained.

Speaking hours before the House vote Tuesday, Mr. Bush said lawmakers would be crossing an ethical line if they approved the main stem cell bill. "Today, the House of Representatives is considering a bill that violates the clear standard I set four years ago. This bill would take us across a critical ethical line by creating new incentives for the ongoing destruction of emerging human life. Crossing this line would be a great mistake," he said.

President Bush has threatened to veto any bill that challenges his 2001 ban on expanded research using embryonic stem cells.

Democratic Congresswoman Carolyn Maloney says Mr. Bush is holding back progress. "The president wants to create a culture of life. Stem cell research offers scientists the opportunity to extend life, and the quality of life for current and future generations of Americans," he said.

The Castle legislation needed significantly more votes than the 218 minimum it needed for passage to overcome a veto. But a similar version to be considered in the Senate has bipartisan support, although at least one conservative senator has vowed to fiercely oppose the measure.

Another bill approved Tuesday, sponsored by New Jersey Republican Chris Smith, did not challenge the president's position, but aims to expand research involving human adult stem cells and those from umbilical cords.

"We are on the threshold of systematically turning medical waste, umbilical cords and placentas, into medical miracles for huge numbers of very sick and terminally ill patients who suffer from such maladies as leukemia and sickle cell anemia," he said.

That bill would establish a nationwide database and stem cell transplantation system, which along with a parallel one for bone marrow would make it easier for physicians and patients to obtain information and matches.