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A citizen-led initiative in Mississippi that would impose the country’s tightest regulations yet on abortion and birth control might create a dilemma for moderate Republicans.

Mississippians will vote on the “personhood” amendment Tuesday that would change the definition of a person to include “every human being from the moment of fertilization, cloning or the functional equivalent thereof.”

Although seemingly simple and broad in its language, Initiative 26 has long-term implications.

It goes beyond what most anti-abortion politicians and groups advocate, which is to define life at conception and limit abortion only to cases of rape, incest and when the mother’s life is in danger.

“Since it’s tied to fertilization, it implicates all sorts of other things, like many methods of hormonal birth control, like preventing implantation after fertilization has occurred, or fertility treatments where embryos are at risk,” said Jonathan F. Will, an assistant professor of law and director of the bioethics and health law center at the University of Mississippi School of Law.

Opponents have dubbed the measure a radical move by the right-wing to suppress women’s rights. Even anti-abortion rights groups are concerned that such a far-reaching initiative would hamper their ability to overturn Roe v. Wade in the Supreme Court, by shifting the discussion to the definition of human life.

For moderate Republicans, the amendment – and the national attention it is receiving – poses a new challenge. Many Republicans on the center-right want to limit abortions but do not want to become bait for groups that say Initiative 26 squashes women’s rights.

Mississippi Gov. Haley Barbour has already appeared to do a flip-flop on the issue this week. He said on MSNBC Wednesday that he was concerned by the ambiguous language of the amendment, and the idea it could potentially hamper fertility treatments. But today, Barbour cast an absentee ballot in favor of Initiative 26, with an ambiguous explanation of his own.

“I have some concerns about it,” Barbour said in a statement. “But I think all and all, I believe life begins at conception so I think the right thing to do was to vote for it.”

Other Republicans have found themselves caught in a similar place. New Jersey Gov. Chris Christie is backing Republican gubernatorial candidate Phil Bryant, who supports the initiative. But Christie – considered by many to be a model of moderate conservatives – has remained mum on the issue. His camp has only said that just because Christies is campaigning for Bryant, it doesn’t mean he also endorses the amendment. But he hasn’t spoken against it either.

The Democratic National Committee took out an ad charging 2012 GOP presidential candidate Mitt Romney of supporting the “personhood” amendment, the “most extreme attack on a woman’s right to choose in a generation.” But the ad is misleading because Romney has said he would support a constitutional amendment stating that life begins at conception, not fertilization, as the Mississippi measure states. The 2012 candidate hasn’t commented on Initiative 26.

The Mississippi measure has opened up a new chapter in the abortion debate. Anti-abortion groups gained fresh momentum after Republicans won the U.S. House of Representatives, and many state legislatures, by a landslide last year. Many of these groups believe they are getting increasingly closer to taking the issue to the Supreme Court and overturning the controversial Roe v. Wade decision.

But Initiative 26, in many conservatives’ eyes, threatens to split the anti-abortion movement and change the direction of the discussion.

“Even opponents of abortion rights who would like nothing more than to give the courts an opportunity to reverse Roe v. Wade may find this amendment a bad vehicle for doing so,” professor Will and Harvard professor I. Glenn Cohen wrote in an op-ed in the New York Times. “Courts frequently read ambiguous language as a strategy to avoid raising serious constitutional questions. By endorsing a ballot initiative that is deeply ambiguous, pro-life constituencies could be inviting courts to read the amendment in a way that sidesteps the very constitutional question they want to force.”

Similar initiatives by Parenthood USA, which is behind Initiative 26, have been unsuccessful. The measure was voted down twice in Colorado, in 2008 and 2010.

Proponents say it’s likely to win in Mississippi but the national attention that has been cast on it has also brought out the opposition and could hamper its success.

Even if it passes, the road to implementation will be long. Will points out that the proposed amendment does not state whether it would be self executing, meaning that the Mississippi law will change once it passes, or whether it needs to be accompanied by legislative action.