Spoiling for a veto fight, Congress cleared legislation Thursday easing restrictions on federal funding for embryonic stem cell research.
The House vote to send the measure to President Bush was 247-176, 35 short of the level needed to override a second veto in as many years on the issue.
"For many, embryonic stem cell research is the most promising source of potential treatments and cures" for debilitating disease, said Rep. Diana DeGette, D-Colo., the bill's leading advocate.
"Unfortunately, because of the stubbornness of one man — President Bush — these people continue to suffer as they wait," she added.
The president was unpersuaded.
"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," he said in a statement in Germany, where he was attending a summit of world leaders.
"Crossing that line would be a grave mistake. For that reason, I will veto the bill passed today," he added.
Bush's written statement echoed criticism leveled in an hour-long debate on the House floor, where opponents of the measure said the research requires the destruction of human embryos, and that alternatives have shown more promise.
"You're talking about spare embryos now but if it ever did work ... it would require the killing of millions of embryos," said Rep. Chris Smith, R-N.J.
He also said a recent report by the U.S. Catholic Conference listed numerous breakthroughs involving research conducted on adult stem cells, cord blood and amniotic fluid, none of which involve the destruction of a human embryo.
The measure drew the support of 210 Democrats and 37 Republicans. Opponents included 16 Democrats and 160 Republicans.
Public opinion polls show widespread support for stem cell research, which supporters say could lead to treatment of diseases as diverse as Alzheimer's and juvenile diabetes. Democrats made the measure one of their top priorities when they took control of Congress in January — knowing full well that Bush stood ready to veto it.
The president made his position clear weeks ago when he said the legislation "crosses a moral line that I and many others find troubling."
Democratic aides said House Speaker Nancy Pelosi of California and Senate Majority Leader Harry Reid of Nevada intended to stage a mid-afternoon ceremony to dramatize the passage of the bill.
They held a similar event earlier in the year when Congress approved another high-profile bill that faced a veto, a measure containing a timetable for a troop withdrawal from Iraq.
Bush vetoed that bill on May 1, and as expected, the House failed to override his veto.
The House approved an initial stem cell measure within days of convening on a 253-174 vote that was short of a veto-proof majority. The Senate passed a slightly different measure in April, 63-34. The House needed to vote on the bill again to send it to the president.
There was no federal money for embryonic stem cell research until Bush announced on Aug. 9, 2001, that his administration would make it available for lines of stem cells that already were in existence. Elected with the strong support of abortion foes and other conservatives, he said at the time his decision was designed to balance concerns about "protecting life and improving life."
He also limited the funds to cell lines derived from embryos that were surplus at fertility clinics, and that had been donated from adults who had given informed consent.
Advocates of the veto-threatened legislation argue that the number of stem cell lines available for research is smaller than needed, and that some of the material has become contaminated over time by mouse embryonic skin cells that typically are placed at the bottom of culture dishes used in the research.
The bill would permit funding for research on embryonic stem cells regardless of the date of their creation, as long as they were donated from in-vitro fertilization clinics, they would "otherwise be discarded" and donors gave their approval.
Separately, three teams of researchers reported Wednesday they had found a way to produce embryonic stem cells without destroying embryos — but in mice. They got ordinary skin cells to act like the embryonic cells, which can develop into all types of tissue.
In a prelude to the stem cell vote in Congress, House Republicans engineered the defeat of legislation to ban human reproductive cloning. The 213-204 vote against the measure was well short of the two-thirds majority needed for passage.
Critics said it would facilitate the creation of cloned human embryos to be used in research and then destroyed.