WASHINGTON -- In the rush to pass legislation before the August recess, Democrats made a final -- and unsuccessful -- attempt yesterday to force Senate Majority Leader Bill Frist to bring up Pennsylvania Sen. Arlen Specter's legislation expanding federal funding for embryonic stem cell research.

The House passed the Stem Cell Research Enhancement Act with the support of 50 Republicans two months ago, but momentum to pass an identical measure in the Senate appears to have sputtered to a halt.

Frist's refusal yesterday to consider the bill means the measure will not come up before September.

That angered some Democrats, who said the legislation's bipartisan support in the Republican-dominated House should have made it more of a priority than some other measures the Senate is considering in this final week.

"Every day we delay consideration of this bill is another day we deny hope to millions of Americans and people throughout the world with Parkinson's disease, Alzheimer's, spinal cord injuries, heart disease, diabetes, to name only a few," said Senate Minority Leader Harry Reid, D-Nev., after attempting to bring up Republican Specter's legislation and an uncontroversial measure that would provide federal funding to harvest stem cells from umbilical cord blood. That bill has also passed the House.

But Frist, a heart surgeon who controls the agenda as majority leader, has said he will not bring up Specter's legislation unless he can get all 100 senators to agree to "clean" votes on six or seven pieces of legislation relating to bioethical issues -- meaning senators would vote on each bill without offering amendments sometimes used to kill legislation.

"I'm not going to give up on the stem cell issue because the research is hugely promising," the Tennessee Republican said yesterday after explaining that he had been unable to get an agreement. "I hope that after we get back ... we will be able to address the issue."

Frist said he has ethical concerns about the bill sponsored by Specter and Sen. Tom Harkin, D-Iowa, which would permit federal funding for stem cell research using donated embryos left over at in-vitro fertilization clinics (as long as they would otherwise be discarded).

But he said he was committed to allowing debate, as long as the other bills are debated simultaneously.

"I feel, as leader, that it's an important issue that does have to be addressed," Frist said. But "to bring up a bill and just pass it today, which strikes at the moral and ethical fundamentals of each and every one of us, and to try to take that single bill, or just two bills, through without respecting my colleagues -- I just can't do that."

Frist added that he is interested in exploring several new technologies that may allow embryonic stem cell research without the destruction of embryos -- techniques some researchers say are largely unproven. Harkin has said the rush to draft legislation on those alternative techniques is a game of "smoke and mirrors" by Republicans opposed to the bill.

President Bush has threatened to veto Specter's legislation, because, he says, it crosses a "critical ethical line, by creating new incentives for the ongoing destruction of emerging human life."

Some Democrats believe White House officials are pressuring Frist to prevent the bill from coming up, as well as encouraging alternatives that detract support from the Specter-Harkin bill.

Specter's bill, which was sponsored by Reps. Michael Castle, R-Del., and Diana DeGette, D-Colo., in the House, expands the limits Bush set on funding for embryonic stem cell research. On Aug. 9, 2001, Bush said federal funding for the research would be limited to stem cell lines available on that date. Few of those lines have come to fruition.

Two-thirds of the members in each house would have to agree to override a presidential veto.

If Frist cannot get unanimous consent to bring up the group of bill dealing with bioethical issues, Specter has said he will try to attach the embryonic stem cell legislation to a key spending bill providing money for health and human services, which he oversees as chairman of the Senate Appropriations labor, health and human services subcommittee.

"I don't like to put it on an appropriations bill but we waited long enough," Specter said last week.

Harkin said yesterday that he was worried that Republicans opposed to the bill would try to defeat that effort as well, by rolling the health spending bill into a larger omnibus bill that would give the embryonic stem cell proponents in the Senate less control.

But Utah Sen. Orrin Hatch, a conservative Republican who is a key co-sponsor of Specter's bill, said yesterday he has faith Frist will try to bring up the measure in September.