The Senate appears ready to approve expanded federal funding for embryonic stem-cell research.
President Bush has already promised to veto the bill, just as he did last year, and Senate supporters aren't expected to have enough votes for an override.
But they say Americans clearly support the research, which many believe offers the potential of treatment for many diseases. They promise to keep trying, and California Senator Dianne Feinstein says the bill will eventually become law.
Opponents say the research is immoral because it requires the destruction of embryos. Many of them are supporting an alternative, which has the president's backing. It would permit research on cells derived from amniotic fluid and placentas and from embryos that have died naturally.