The bill's supporters contend the government's funds would be authorized only for research on some of the approximately 400,000 fertilized embryos that are discarded annually by fertility clinics because the would-be parents no longer want them.

The bill would repeal the Bush administration's nearly four-year old restriction on the research, allowing scientists to use government funds to experiment on cells taken from embryos slated to be discarded by fertility clinics.

Arlen Specter, Senate Judiciary chairman, said the measure has the support of at least 60 senators, more than enough to beat back a conservative-led filibuster that would kill the bill. Specter said he believes as many as 67 senators would support the bill, enough to override a veto President Bush has promised if it reaches his desk.

Specter said he'll first appeal to Frist to schedule a vote, but will try to attach the stem cell measure to other bills if Frist refuses. The bill's supporters include Senate Democratic leader Harry Reid, who also called on Frist to allow a vote on the measure the House passed Tuesday.

"There are so many people with Alzheimer's and Parkinson's and heart disease and cancer. I know some of them myself: [I] look in the mirror every day, barely recognize myself," said Specter, a Pennsylvania Republican who is undergoing chemotherapy treatments for Hodgkin's disease. "And not to have the availability of the best in medical care is simply atrocious.

"If a veto threat is going to come from the White House, then the response from the Congress is to override the veto if we can," Specter said.

A Renewed Sense of Optimism

Frist, a heart surgeon who has been a leading voice on medical issues in the Senate, has supported Bush's ban on federal money for embryonic stem cell research. Yesterday, he would not say whether he'll bring up the House-passed bill for a vote in the Senate.

Frist did say he expects the Senate will "do something" on the issue of stem cell research within months. Frist said the bipartisan agreement on judges, which temporarily defused a contentious issue that could have tied the Senate in knots, will allow the Senate to proceed in a new atmosphere of civility.

"There are other issues which have not been on the agenda, like stem cells, that, in the future, we [will] have the opportunity to discuss," said Frist, a Tennessee Republican. "I personally look forward to the opportunity to review the science, to review the ethical considerations around the use of stem cells for research."

The tough talk from Specter and other prominent senators reflected a renewed sense of optimism among supporters of embryonic stem cell research, a promising area of science. But the issue is another major headache for Frist, who is still coping with the fallout from the Senate's compromise over judicial appointments, a deal in which seven members of his own party bucked his leadership.

Destruction of Human Embryos

Social conservatives oppose research on embryonic stem cells because it requires the destruction of human embryos. Scientists say research on embryonic stem cells, unspecialized cells that could be used to repair human tissue, is considered more promising than work on adult stem cell lines, which are more limited in their use in the human body.

Because the embryonic lines have not been assigned, they can be transformed into more types of cells, possibly helping in treatments of crippling diseases. Adult stem cells are collected from the umbilical cord after a woman gives birth.

The bill's supporters contend the government's funds would be authorized only for research on some of the approximately 400,000 fertilized embryos that are discarded annually by fertility clinics because the would-be parents no longer want them. The embryos are harvested as part of in vitro fertilization, which typically yields many more than are needed for fertility treatments.

Frist probably will face more pressure from conservatives -- some of whom are angry that GOP senators bypassed Frist to cut a deal with the Democrats on Bush's judicial nominees -- to block an expansion of experimentation on stem cells.

If the stem cell measure reaches the Senate floor, conservative senators, led by Senator Sam Brownback, Republican of Kansas, say they will use a filibuster to stop it. Supporters, however, expressed confidence that they have enough votes to counter that maneuver.

Fifty House Republicans Voted with Democrats

On Tuesday, the Republican-led House of Representatives voted, 238 to 194, to lift the Bush administration's ban on federal funding for embryonic stem cell research. Fifty House Republicans voted with Democrats in favor of the bill, even though House Republican leaders opposed it. The bill, however, fell short of the 290 votes it would need to override a veto by Bush.

Presidential vetoes can be overridden, but it takes a two-thirds' majority vote in both the House and the Senate to do it. Bush has not used his veto pen since taking office in 2001, but he has vowed to use it on the stem cell bill if it reaches his desk.

House majority leader Tom DeLay, a leading critic of the bill, commended Bush's stance. He said social conservatives were pleased even though they came out on the losing side of the House stem cell vote, because the issue was fully debated and there aren't enough supporters to override Bush's veto.

"That bill that passed the House yesterday is not going to become law," said DeLay, a Texas Republican. "They cannot get over the fact that you're killing an embryo in order to do research."

Bush reiterated his veto promise yesterday, with his press secretary calling the use of embryos for research an ethical line that the president will not cross.

"I've made my position clear, and I will be vetoing the bill they send to me if it were to pass the United States Senate," Bush said in the Oval Office.

Most People Favor the Research

At the news conference yesterday, Specter was joined by two fellow Republican senators, Orrin G. Hatch of Utah and Gordon Smith of Oregon, along with Democrats Edward M. Kennedy of Massachusetts, Dianne Feinstein of California, and Tom Harkin of Iowa. The bill's House sponsors ceremonially handed the senators a copy of the bill with a red bow on top.

Though polls indicate most people favor the research, Specter predicted that further public understanding of the issue could change votes in the House, perhaps enough to gain the two-thirds' majority needed to neutralize a veto.

If not, he said, he and other Republicans would try to get Bush to change his mind.

Hatch, who opposes abortion, said that issue and stem cell research are wrongfully linked.

"It is possible to be both anti abortion and pro embryonic stem cell research," Hatch said. "We want to help the unborn, but we also want to help the living."

Kennedy said Tuesday's House vote shows that Bush and other Republicans are out of synch with the country's mainstream beliefs.

"It is supported in red states and blue states, by Republicans and Democrats, and by supporters and opponents of Roe v. Wade," Kennedy said. "The American people are saying loud and clear that they want the president and Congress to focus on what really matters to them."