LITTLE ROCK, Ark. — So-called tort reform has been an easy sell in states controlled by Republicans, and backers of a lawsuit-limiting proposal on the ballot in Arkansas this fall expected little trouble winning passage until they ran into a surprising obstacle from a reliable conservative ally.

A Christian group has begun rallying churches and abortion opponents against the measure, saying that limiting damage awards in lawsuits sets an arbitrary value on human life, contrary to anti-abortion beliefs, and conflicts with biblical principles of justice and helping the poor.

Proponents of the measure are stunned by the opposition and worried that it could stir dissension among conservatives who must work together on numerous issues.

“The biggest problem is not the damage” to the tort reform proposal, said Republican Rep. Bob Ballinger, a sponsor of that measure. “The biggest hurdle is the damage to the pro-life cause.”

The religious argument also could offer tort reform opponents in other states a new weapon for fighting limits. The legal restrictions have been making headway in recent years as the GOP has won control of roughly two-thirds of state legislatures.

Arkansas’ measure is an effort by an array of pro-business groups, including the state Chamber of Commerce, to reinstate legal caps that have been chipped away over the years by court rulings.

The amendment would cap damages for noneconomic losses, such as pain and psychological distress, to $500,000 and punitive damages to $500,000 or three times the amount of compensatory damages awarded, whichever is higher. It also would cap attorneys’ contingency fees at one third of the net amount recovered.

The proposal doesn’t cap economic damages, which go toward verifiable losses such as medical expenses as well as past and future wages. But the conservative Family Council Action Committee argues that putting a cap on other damages devalues the lives of those with no income, such as the elderly and stay-at-home parents, who would receive little compensation for pain and suffering.