People in the state of South Dakota are confronting a historic opportunity to sway a tortuous national debate by making a choice no statewide electorate in the U.S. has faced before: whether to approve a sweeping ban on virtually all abortions.

On Nov. 7, when American voters will choose a new Congress, governors in 36 states and decide whether to approve various ballot initiatives, South Dakota voters will vote on a measure that would allow abortions only to save a pregnant woman's life. It makes no exception for other health concerns, or for cases of rape or incest; a doctor performing illegal abortions could face five years in prison.

The state Legislature passed the law overwhelmingly in February, expecting it to be challenged in court and perhaps lead to a U.S. Supreme Court reversal of the 1973 Roe v. Wade decision legalizing abortion. Instead of suing, opponents swiftly collected signatures to force a referendum; the law will be scrapped if voters reject it.

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"None of us think abortion is a desirable thing," said Tom Dean, a family physician who hosted a recent discussion among friends. "But it's not a problem for government to solve by passing a rigid law."

Yet Lynn Ogren, who helps her husband run a sheep and cattle ranch, choked up with emotion as she explained her support for the ban.

"I value every child's life, whether it's from a rape or not," she told her friends. "Who's fighting for these kids?"

Each side depicts the other as dominated by out-of-state groups — and indeed such forces are active, viewing the vote as an unprecedented gauge of public sentiment on abortion. The Rev. Jerry Falwell has urged his conservative followers to donate in support of the ban; Planned Parenthood and NARAL Pro-Choice America have raised funds to oppose it.

"We're David, they're Goliath," contended Leslee Unruh, head of the campaign group supporting the ban. Parked outside her VoteYesForLife.com office in Sioux Falls were cars with a blunt bumper sticker: "The Killing Stops Here."

The most recent independent poll, in July, found 47 percent of South Dakota voters opposed the ban, 39 percent favored it, 14 percent were undecided. When asked if they would approve a ban with exceptions for rape and incest, support rose to 59 percent.

Unruh, who had an abortion years ago that she now regrets, says momentum is turning as more voters hear her side's core message: Abortion hurts women. In the event of defeat, she vows to keep fighting.

"Sometimes it's not about votes — it's about the truth," she said.

Jan Nicolay, a former school principal and Republican state legislator, is co-chair of the campaign to keep abortion legal. She knows the stakes are high.

"People from other states are telling me, 'You're in the limelight. Good luck. Please do everything you can to defeat it,"' she said.

Among her colleagues is Russ Tarver, a retired Methodist minister who signed a statement against the abortion ban along with 16 other ministers. "Some legislators were stunned to learn there were pastors on the other side of the issue," he said.

If the ban is defeated, anti-abortion activists might try again later with a milder version making exceptions for rape and incest, but the outcome would be heralded nationally as a major victory for abortion rights. If the ban is approved, several other state legislatures might follow South Dakota's example — building momentum for a possible Supreme Court review of Roe v. Wade.

The ban's supporters note that the measure allows rape and incest victims to get emergency contraception, which is effective if taken within 72 hours. Opponents say emergency contraception is not widely available in South Dakota, and argue that many victims are too overwrought to seek prompt help.

One of the legislators responsible for the toughly worded measure is House Majority Leader Larry Rhoden, a Republican cattle rancher. He was swayed by women's testimony that their abortions left emotional scars, but now — aware of polls showing his side behind — he has second thoughts.

"I've spent a great deal of time and thought wondering if it would have been wiser to write in the exceptions," he said. "We have a long row to hoe based on the numbers I've seen."

In some ways, South Dakota is an odd venue for the showdown. It has had no resident abortion provider for 10 years, and most of its 800 or so annual abortions are performed at an often-picketed Planned Parenthood clinic in Sioux Falls by doctors flying in once a week from Minnesota.

Sarah Stoesz, president of Planned Parenthood's Minnesota/Dakotas chapter, said even people on the sidelines of the abortion debate rallied to help the petition drive after lawmakers approved the ban.

"It was a political moment like I've never seen, a spontaneous uprising of grass-roots fury," she said. "Abortion isn't a subject people normally discuss, but this has forced ordinary mainstream people to talk about it."