The split between social conservatives and moderate Republicans over embryonic stem cells could undermine the re-election chances of a Missouri Republican senator who favors long prison terms for those who conduct some types of research.

A coalition of business leaders and medical research institutions is gathering support for a Nov. 7 ballot initiative that would amend the Missouri constitution to safeguard stem cell research and treatments in the state.

Sen. Jim Talent, who faces a strong challenge in November from Democratic state auditor Claire McCaskill, has declined to take a stand on the measure. But he has co-sponsored a Senate bill to ban embryonic stem cell research and impose a million-dollar fine and 10-year jail sentence on violators.

"If Talent comes out in favor of stem cell research, he loses support from the evangelicals," said Max Skidmore, professor of political science at University of Missouri-Kansas City. "If he opposes it, he'll lose support from the business community that otherwise might support him."

The issue has divided Republicans, pitting former first lady Nancy Reagan against President Bush and Senate Majority Leader Bill Frist, R-Tenn., against religious conservatives.

Reagan and others argue that the research offers scientific promise that could cure diseases such as Alzheimer's that her late husband, former President Reagan, suffered from for years. Anti-abortion conservatives contend that the research destroys days-old fertilized embryos and amounts to the taking of human life.

Frist angered conservatives last year when he reversed course to support expanded government-funded research on embryonic stem cells. In August 2001, Bush imposed restrictions on public funding for newly developed embryonic stem cell lines.

Talent says he'll make a decision after voters decide whether they want the issue on the ballot. A massive signature campaign is under way.

"I'm opposed to cloning, but I support stem cell research," Talent told The Associated Press in a recent interview. "The technology is changing all the time and so I'm always considering whether there is a better way to strike the balance."

That answer fails to address the major issue in the debate: whether to allow scientists in Missouri to conduct somatic cell nuclear transfer, also known as therapeutic cloning. Anti-abortion groups claim the procedure destroys human life because researchers grow cells using the altered nucleus of a human egg.

Democrats have hammered Talent over the issue for months, saying he's not bold enough to stand up to either his campaign donors or his political base.

The business and medical community, which has rallied around the measure, wants to protect the state's largest medical research institutions from repeated efforts in the state legislature to criminalize stem cell research.

The Stowers Institute for Medical Research in Kansas City, for example, has had to turn away researchers and delay plans for a major expansion. Officials are concerned scientists might one day face criminal charges for pursuing stem cell research, said William Neaves, president and chief executive officer at Stowers.

Some of Missouri's most influential Republicans have lined up to back the effort, including former Sen. John Danforth, who appears in TV commercials supporting the ballot measure. Danforth has complained about the Christian right taking over the GOP.

Democrat McCaskill turned up the heat this month when she came out strongly in favor of the ballot initiative.

Talent may face pressure to modify his views in light of polls showing Missouri voters favor the ballot initiative by a 2-to-1 margin. Recent polls also show him and McCaskill in a dead heat.

If he moderates his views, however, he faces the wrath of his longtime boosters in the anti-abortion community who strongly oppose the measure.

"If he doesn't take a clear position on the pro-life side, it's going to hurt him, no question about it," said Sam Lee, director of Campaign Life Missouri. "People are just not going to work for him."

Lee and other anti-abortion activists say killing the stem-cell initiative is more important to them than re-electing Talent.

"This issue has been very divisive in the Republican Party," said Pam Fichter, president of Missouri Right to Life. "You can't help but extrapolate that and say it would hurt the Republican ticket at all levels."

While many Republicans in the business community are rallying behind the ballot measure, not all believe it will have a negative effect on Talent.

St. Louis businessman Sam Fox, an influential GOP contributor, said Republicans like him who back stem-cell research still support Talent.

"The Republican Party is a big tent, and you have many different views and not everyone shares the same view," he said.