Americans who believe embryonic stem cells could one day cure their cancers, their parents'degenerative diseases or their children's diabetes may soon reach a crossroads: a final vote by Congress to lift President Bush's ban on federal funding for research on new embryonic stem cell lines.

Sens. Arlen Specter of Pennsylvania and Orrin Hatch of Utah, two Republicans leading a bipartisan coalition to force such a vote, say the issue should reach the Senate floor sometime in May or June after languishing for months.

They predict they have enough votes to lift the ban and say they believe Senate Majority Leader Bill Frist, a Tennessee Republican, will make the push. But they say they are prepared to take matters into their own hands should he hesitate.

Hatch, whose otherwise socially conservative record makes him a powerful ally for proponents of the research, said of Frist, "Now is the right time. He has to bring it up, or we'll bring it up."

If they go forward before Congress recesses for the summer, however, political strategists on both sides of the aisle say they could hand the Democrats an advantage in this year's midterm elections and impact the Republican presidential primary elections two years from now as well.

Perhaps even more than the discord over how to curb illegal immigration without devastating the economy, the debate over whether research that necessitates the destruction of embryos is tantamount to live-saving science, or murder, is one that divides the Republican Party.

"I think time has passed the Bush position by, to be candid with you," said Frank Carlucci, a former deputy CIA director and a defense secretary under President Ronald Reagan. Carlucci, now 75, is living with Parkinson's disease and favors lifting the ban on federal funding. "It would be a major step forward for science."

Amanda Banks, an analyst with the lobbying arm of the conservative national organization Focus on the Family, disagrees.

"If members who are otherwise pro-life vote in favor of . . . stem cell research, they will no longer be pro-life in our view," she said.

"It's a wedge issue, in that it separates the true pro-lifers from the compromisers," Banks said.

Ten months ago, the GOP-led House of Representatives put the wheels in motion for this debate, defying Bush's veto threat and voting 238-194 to allow federal money to be spent on research using frozen embryos otherwise slated to be discarded by fertility clinics.

Two months after that, Frist, a physician, alienated many social conservatives and gambled with his own prospects for a presidential run by saying he now favored expanded embryonic stem cell research and would bring the matter to a vote.

But the vote never came, postponed by Hurricane Katrina, two Supreme Court confirmations, and protracted debates over spending, military policy and immigration.

Overall, Americans increasingly support embryonic stem-cell research as scientists around the world look for ways to use technology to treat elusive diseases. Because embryonic stem cells are so young they don't yet perform specialized tasks, scientists believe they could be trained to repair skin or organs, perhaps even brains, damaged by disease.

But among Republican voters, the issue divides ideological moderates from social conservatives. Gallup surveys found Republicans last year evenly divided - 47 percent for and 47 percent against -over the acceptability of embryonic stem cell research.

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