Congressional Democrats are spoiling for their second veto fight of the spring with President George W. Bush, this one centered on embryonic stem cell research and its disease-fighting potential. House supporters of legislation to loosen restrictions on the use of federal funds for the high-tech research claim more than enough votes to send the measure to the White House on Thursday. Less clear is whether they also will have the votes to override the veto the president has pledged. Bush made his position clear weeks ago when he said the legislation, which involves the destruction of human embryos, "crosses a moral line that I and many others find troubling." Public polls show strong support for the research, which supporters say could lead to treatment of diseases including Alzheimer's and juvenile diabetes. Democratic congressional leaders arranged to dispatch the measure to the White House with a flourish. Democratic aides said House Speaker Nancy Pelosi and Senate Majority Leader Harry Reid intended to stage a ceremony to dramatize the passage of the bill. They held a similar event earlier in the year when Congress approved legislation containing a troop withdrawal timetable for the Iraq war. Bush vetoed that bill on May 1, and as expected, the House failed to override his veto. Democrats made the legislation a top priority when they took control of the House and Senate in January. 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 August 9, 2001, that his administration would make it available for lines of stem cells that 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.