WASHINGTON — President Bush vowed yesterday to veto legislation intended to ease the restrictions he imposed on stem-cell research in 2001.

A bipartisan team in the House has collected 201 sponsors and believes it has enough other supporters to reach the 218 votes necessary to pass the measure as early as next week and send it to the Senate. But Bush dashed their hopes that he would allow it to become law without a fight.

"I made it 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'm against that. And therefore, if the bill does that, I will veto it," he said at a White House photo session with the prime minister of Denmark.

Bush has never vetoed a bill, and it's not clear whether this one will reach his desk. The Senate hasn't agreed to consider the legislation.

Bush also condemned reports about the latest cloning advance by South Korean scientists. "I'm very concerned about cloning," Bush said. "I worry about a world in which cloning becomes acceptable."

The president's comments seemed aimed at putting the brakes on the House bill gaining momentum on Capitol Hill. That bill would lift Bush's ban on using federal dollars to do research on embryonic stem-cell lines developed after August 2001. The bill does not authorize federal funding for experiments that create embryos through cloning or other means.

The president's veto threat drew immediate reaction from sponsors of the bipartisan bill, Reps. Mike Castle, R-Del., and Diana DeGette, D-Colo.

Castle said the legislation would not allow the cloning of embryos or embryo destruction. Instead, it would let government-funded researchers work with stem cells culled from embryos left over from fertility treatments.

"The bottom line is, when a couple has decided to discard their excess embryos, they are either going to be discarded as medical waste or they can be donated for research," Castle said.

DeGette said: "It's disappointing that the president would threaten to use his first veto on a bill that holds promise for cures to diseases that affect millions of Americans."

Stem cells are building blocks that give rise to every tissue in the body. Supporters of embryonic stem-cell research, including former first lady Nancy Reagan, say it could lead to cures for Alzheimer's, Parkinson's and other degenerative brain and nerve diseases.

Thursday's South Korean announcement seemed to fuel hopes for such cures. Researchers at Seoul National University produced cloned stem cells tailored to individual patients. Eventually, researchers hope the technique will allow them to regrow damaged organs or spinal nerves, cure diabetes by replacing insulin-producing cells, and cure myriad other diseases and injuries.

Bush, after lengthy deliberation, placed limits in 2001 on federal funding for research on lines of embryonic stem cells.

A study published in January in the journal Nature said almost all of those cells have been contaminated by mouse proteins that would probably make humans reject therapies.

Stem cells are extracted from days-old embryos, which are destroyed in the process. Bush and some religious and conservative groups who believe life begins at conception oppose the research and don't think tax money should be used to finance it.

House Republicans are supporting an alternative bill that encourages stem-cell research that uses blood from umbilical cords. Extracting stem cells from cord blood does not require the destruction of an embryo.

White House deputy press secretary Trent Duffy said the administration is looking favorably at that bill, but he stopped short of endorsing the legislation.

In the Senate, Sen. Arlen Specter, R-Pa., who is undergoing chemotherapy for Hodgkin's disease, is pushing stem-cell legislation with Sens. Orrin Hatch of Utah, a conservative Republican, and Dianne Feinstein of California, a moderate Democrat. They said their bill would make reproductive cloning, to produce a baby, a crime punishable by up to 10 years. But they want to allow for cloning for the purpose of obtaining stem cells to be used in treating disease.

Bush began yesterday at the National Catholic Prayer Breakfast, where he reaffirmed his position on sensitive issues such as abortion and stem-cell research. He urged people to "pray that America uses the gift of freedom to build a culture of life." And he recalled the legacy of the late Pope John Paul II, saying, "The best way to honor this great champion of human freedom is to continue to build a culture of life where the strong protect the weak."

Material from The Associated Press, The Washington Post, Knight Ridder Newspapers and Reuters is included in this report.