WASHINGTON — The House approved expanding federal funding for human embryonic stem-cell research, while falling short of the support needed to override President Bush’s threatened veto.

The House’s 247–176 vote fell more than 30 short of the two-thirds majority needed to override a veto.

Minutes after the vote, Mr. Bush vowed to block the measure.

“If this bill were to become law, American taxpayers would for the first time in our history be compelled to support the deliberate destruction of human embryos,” Mr. Bush said in a written statement from Heiligendamm, Germany, where he is attending the annual Group of Eight leaders’ summit. “Crossing that line would be a grave mistake. For that reason I will veto the bill passed today.”

Democrats said the veto will demonstrate Mr. Bush’s indifference to public support for the research and send his falling approval rating even lower.

“We should get this to the president’s desk as soon as possible so he can veto it and be even more unpopular with the American people,” said Rep. Dennis Cardoza, a Democrat of California.

The House Republican leader, Rep. John Boehner of Ohio, said Democrats, knowing the legislation would be vetoed, held the vote for public relations, not policy goals.

“This is politics,” Mr. Boehner said. “It is not about expanding research.”

The legislation, already passed by the Senate, would allow federal funding for stem-cell research using excess human embryos that were created for fertility treatments and would otherwise be discarded.

Shares of companies developing stem cells fell after the vote fell short of the level needed to override a Bush veto.

Menlo Park, California-based Geron Corp. fell 35 cents, or 4%, to $8.50 as of 2:26 p.m. in Nasdaq Stock Market composite trading. Shares of Cambridge, Massachusetts-based Viacell fell 16 cents, or 2.7%, to $5.76. Advanced Cell Technology Inc, based in Alameda, Calif., fell 3 cents, or 3.9%, to 71 cents in over-the-counter trading.

Democrats said America shouldn’t handcuff scientific research into possible cures for chronic diseases.

“How can we tell someone who has a family member with Alzheimer’s disease that we won’t do everything possible” to find a cure, Rep. Lynn Woolsey, a Democrat of California, asked.

Opponents argued that using embryos for speculative research is immoral. “If it ever worked there would be an insatiable demand,” for human embryos, Rep. Chris Smith, a Republican of New Jersey, said.

The debate is whether “taxpayer funds should be used to destroy for scientific research what many consider to be human life,” said Rep. Jeb Hensarling, a Republican of Texas. “Let’s fund stem-cell research, but let’s fund it ethically.”

Advocates say scientists may be able to replicate human tissue cells taken from discarded human embryos, possibly leading to cures for diseases such as Alzheimer’s, Parkinson’s, juvenile diabetes, and other ailments.

Scientists yesterday reported that they were able to take ordinary skin cells from mice and get them to act like embryonic cells, with their unlimited potential to become other cell types.

Democrats said such research is no substitute for work with human embryonic stem cells.

Mr. Bush issued an executive order in August 2001 prohibiting federal support for research using newly created embryonic stem cells. He allowed research to continue on about 71 pre-existing embryonic stem-cell lines, of which 21 remain viable for research.

Mr. Bush used the first veto of his presidency to block legislation to ease those restrictions.

The president’s approval rating fell to 32%, matching the lowest of his presidency, in an AP-Ipso poll conducted June 4–6.

Sixty-four percent of respondents say stem-cell research using cells from human embryos is morally acceptable, according to a May 10–13 poll of 1,003 adults nationwide by the Gallup Organization.

“It is clear that a vast majority of the American people, and a majority of the Congress, want to see this policy changed,” said Sean Tipton, a spokesman for the Coalition for the Advancement of Medical Research, an umbrella group of organizations that support federal funding for human embryonic stem-cell research.