This vote was on final passage of a bill to broaden federal spending on embryonic stem cell research.

The legislation would allow federal grants to be used for research on embryos donated by in vitro fertility clinics so long as the embryos were not created for scientific purposes and otherwise would be thrown away. The donors of the embryos would also have to give their consent and could not be paid for the embryos.

Additionally, the bill would authorize the Health and Human Services Department to conduct research involving human embryonic stem cells that meet specific criteria, regardless of when stem cells were derived from a human embryo. The political and policy fight over this issue began in 2001, when President Bush issued an executive order that allowed federal funding only on embryonic stem cell lines created before August 9, 2001.

Bush vetoed an identical bill last year, and the House fell 51 votes short of the two-thirds majority needed to override his veto.

Many Republicans liken research on embryos to abortion, which they oppose as unethical. Supporters of the research, including most Democrats, believe that it promises life-saving medical treatments. They point out that the research is going to be done anyway, and by denying federal funds the United States is simply allowing private research centers around the world to get ahead in curing various diseases. Republican critics counter that research on stem cells has yet to yield life-saving treatments.

Bush adamantly opposes the research and has once again threatened to veto the legislation. In a statement, the White House called the bill "seriously flawed legislation that would undo essential ethical protections, and slow the development of new techniques that avoid bio-ethical concerns."

Nonetheless, the House passed the bill by a vote of 253-174, still well short of the two-thirds majority that would be required to override the threatened veto. Thirty-seven Republicans joined all but 16 Democrats in voting for the measure. The bill then headed to the Senate.