An influential Democratic senator is predicting congressional passage of a bill that would expand federally-funded medical research involving embryonic stem cells - despite a veto threat by President Bush. Renewed debate on the controversial subject follows reports of a scientific breakthrough involving stem cells by South Korean researchers.

U.S. tax dollars may only be spent on embryonic stem cell research derived from a small number of previously-destroyed embryos - where, as President Bush once noted, "the life-and-death decision had already been made."

But Connecticut Senator Joe Lieberman is co-sponsoring legislation that would allow federally funded programs to use new embryonic stem cell lines.

Speaking on ABC's This Week program, Mr. Lieberman said the proposal has a good chance of passing both houses of Congress. "They understand across party lines that stem cell research holds amazing hope for curing diseases, or better treating diseases like diabetes, Parkinson's and a lot of others. This is bipartisan. In the Senate, I am co-sponsor with [Pennsylvania Republican Senator] Arlen Specter of an identical bill. I think we are going to get it done," he said.

The bill could be brought up for a vote in a matter of days.

President Bush has consistently opposed destroying a viable embryo in order to harvest stem cells. Friday, Mr. Bush repeated his opposition and issued a veto warning. "I have made very clear to the Congress that the use of federal money, taxpayers' money, to promote science which destroys life in order to save life, I am against that. And therefore if the bill does that, I will veto it," he said.

Last week, South Korean researchers announced the successful creation of cloned human embryos using genetic material taken from patients suffering a variety of illnesses and medical conditions. The accomplishment is regarded as a major milestone in stem cell research, because, once introduced into the human body, stem cells are unlikely to be rejected by a patient's immune system if they are genetically identical.

Scientists say human embryonic stem cells are formed in the earliest stages of life and can adapt to become any tissue in the body.

But Anne Graham Lotz, the daughter of ailing evangelical minister Billy Graham, said cures and treatments must not be pursued at any cost. "I have a father who has Parkinson's disease, I have a son who has cancer. I have a mother who has degenerative arthritis. I have a husband who has diabetes. I would not want any one of my family members to benefit from the willful destruction of another human life. An embryo, as tiny as it is, is still a human life created in the image of God," he said.

Others take a different point of view. Dana Reeve is the widow of actor Christopher Reeve, who died last year after a prolonged battle with paralysis. "A lot of people will say, 'You have no right to tamper with human life.' This is not a baby. It is not an embryo. It is pre-embryonic. This is something that would not, once implanted, turn into a human being. There is not a disorder you can name that would not benefit from stem cell research. Eyes, heart, lungs - every part of the body [can benefit]," she said.

Some researchers warn unless restrictions are lifted, the United States could quickly fall behind other nations in stem cell research. Public opinion polls show Americans support stem cell research by about a two-to-one margin.