WASHINGTON — Defying President Bush's threat to impose his first veto, 50 House Republicans joined an overwhelming number of Democrats yesterday to repeal his restrictions on federal funding for embryonic stem-cell research.

The 238-194 vote followed a highly personal, occasionally tearful debate in which lawmakers recounted medical tragedies that had affected their families, while opponents contended that the science is built on destroying human lives.

The legislation, which has strong support in the Senate, would lift a restriction imposed by Bush nearly four years ago that limits federally funded research to fewer than two dozen already existing embryonic stem-cell lines. It would make federal money available for research on stem cells extracted from frozen embryos donated by couples who no longer need them for fertility treatments.

The president and other opponents focused on the fact that the embryos are destroyed in obtaining the cells. House Majority Leader Tom DeLay, R-Texas, called it a "vote to fund with taxpayer dollars the dismemberment of living, distinct human beings for the purposes of medical experimentation."

Rep. Diana DeGette, D-Colo., a co-sponsor of the legislation, countered: "The bill is maddeningly reasonable. It takes embryos that will be thrown out and uses them to the greater good."

About 8,000 unneeded embryos are discarded as hospital waste each year.

With the debate under way at the other end of Pennsylvania Avenue, Bush highlighted his opposition by holding an East Room ceremony surrounded by children whose families had adopted them as embryos. The same families had appeared several hours earlier on Capitol Hill, with parents and children alike sporting stickers that said, "Former Embryo."

"This bill would take us across a critical ethical line by creating new incentives for the ongoing destruction of emerging human life," Bush said. "Crossing this line would be a great mistake."

Polls have shown that the public is strongly supportive of the research, and Nancy Reagan's backing made the issue politically palatable for many conservatives.

House Energy and Commerce Committee Chairman Joe Barton, R-Texas, said the loss of his father to diabetes at age 71 and a brother to liver disease at 44 had shaped his decision to support expanded research.

Rep. James Langevin, D-R.I., whose spine was severed in a gun accident as a teen, spoke from his wheelchair about the promise of stem-cell research.

"Stem-cell research gives us hope and a reason to believe," said the self-described pro-life lawmaker. "I believe one day a child with diabetes will no longer face a lifetime of painful shots and tests. I believe one day families will no longer watch in agony as a loved one with Parkinson's or Alzheimer's declines. And I believe one day, I will walk again."

Rep. Randy "Duke" Cunningham, R-Calif., a conservative who described himself as "100 percent pro-life," choked back tears as he recalled meeting a seriously ill 6-year-old girl at a congressional hearing on medical research. "I don't want another 6-year-old to die," Cunningham said haltingly. "I want to save life."

But Rep. Daniel Lungren, R-Calif., said that his older brother John's 15-year battle with Parkinson's did not obviate his ethical concerns and that he could not support "the destruction of part of the human family."

"The worst mistakes we've ever made in the history of this nation have been when we have defined a part of the human family as less than fully human and done things to them that we would not allow done to ourselves," Lungren said. "We've done it with slavery; we've done it with the Tuskegee medical experiments" on poor black men with syphilis.

Proponents of the bill said that Bush's limits on federal funding have hampered potentially promising treatments for a range of illnesses and put the United States at a competitive disadvantage with nations that have pursued the research more aggressively.

Rep. Christopher Shays, R-Conn., called his support "one of the most important votes I will ever make in Congress."

"I think it's time we recognized the Dark Ages are over," Shays said. "Galileo and Copernicus have been proven right. The world is in fact round; the Earth does revolve around the sun. I believe God gave us intellect to differentiate between imprisoning dogma and sound ethical science."

Opposing the bill, Rep. Henry Hyde, R-Ill. — "I myself am a 992-month-old embryo," he noted — compared the legislation to the failure of a former generation to recognize the humanity of Dred Scott, the slave whose lawsuit for his freedom led to a landmark Supreme Court ruling. "For the first time in our national history, taxpayers' dollars are going to be spent for the killing of innocent human life," Hyde said. "We're going to pay a terrible price for not recognizing the humanity of these little embryos."

Washington Democrats Brian Baird, Norm Dicks, Jay Inslee, Rick Larsen, Jim McDermott and Adam Smith voted for the bill. Republicans Cathy McMorris and Dave Reichert voted against it; Richard "Doc" Hastings didn't vote.

Republican leaders said they do not believe the bill's supporters can achieve the 290 votes needed to override a Bush veto in the House. House Rules Committee Chairman David Dreier, R-Calif., who voted for the bill, said he hopes to negotiate a compromise with the White House to avoid a veto confrontation.

The House on a 430-1 vote approved an alternate bill that would pay for research on stem cells extracted from umbilical-cord blood, with Rep. Ron Paul, R-Texas, a physician who specializes in obstetrics and gynecology, casting the only vote against the bill.

Rep. Jo Ann Emerson, R-Mo., who said she had a "perfect pro-life record," said she recently changed her position to support embryonic stem-cell research after consulting patients, scientists, ethicists and her minister. "Who can say prolonging a life is not pro-life?" she said, one day after her mother-in-law died of an illness she said might have been treated with stem-cell therapy.

Material from the Chicago Tribune, Los Angeles Times, Knight Ridder Newspapers and The Associated Press is included in this report.