Politically, President Bush is on the losing side of federally financed stem-cell research. The public supports it and so, increasingly, does Congress.

The Republican Congress passed a stem-cell-research bill last year and the president vetoed it, the first veto of his presidency. This year, the Democratic Congress passed a similar research bill and this week Mr. Bush used just his third veto.

Indicative of the growing support of using stem cells for research, the second attempt at a bill passed by greater margins than the first, 63-34 in the Senate, just four votes shy of the margin needed to override the president's veto.

Broadly, these bills would have permitted federally funded research into cells obtained, with the donors' permission, from surplus embryos that fertility clinics would otherwise destroy.

Mr. Bush argues, defensibly, that he and others are deeply, morally opposed to the destruction of embryos, even if only a few days old and no bigger than a pencil point, for research purposes and they should not have to see their tax money pay for it.

There is no ban on the research. States and private institutions are free to carry out the research. For example, here in California, voters, in 2004, overwhelming approved Proposition 71 that provided $3 billion in state funding for such research.

In 2001, Mr. Bush did issue an executive order allowing research on pre-existing stem-cell lines, but none on embryos created after the date of the order. But scientists said those lines were either inadequate or tainted, and even though the final outcome is far from a certainty, evidence continued to grow that the all-purpose embryonic stem cell was the most effective replacement for nerves and tissue destroyed by diseases like diabetes, Alzheimer's and Parkinson's.

Following his veto, the president issued another order directing the government to encourage the search for nonembryonic cells, from amniotic fluid or umbilical cords or by reprogramming adult cells.

And perhaps one day that will make this whole debate moot, but the beneficiaries of a cure for wasting diseases and their allies are not inclined to wait.

In what's likely to be a wave of such efforts, the Senate Appropriations Committee came right back and, by a vote of 26-3, attached a rider effectively overturning the ban to a must-pass funding bill for the departments of Labor and Health and Human Services.

Mr. Bush can go on fighting this, even as his own party begins deserting him on the issue, but one day he will almost certainly lose and he may find that the strength of his convictions has left him with no say in how this research will ultimately be conducted.