SIOUX FALLS, S.D. — It takes spunk for Katie Andert to sit in the middle of the Commons, day after day, behind a table festooned with signs demanding "Vote No on 6: Repeal the Abortion Ban."

South Dakota is a distinctly conservative state, and the vast majority of its residents will tell you they are "pro-life." They'll also tell you South Dakotans prize politeness and eschew confrontation. Andert's booth on the Augustana College campus is a bit too in-your-face for most folks.

But Andert, a 21-year-old psychology major, is part of a historic campaign to overturn the nation's toughest anti-abortion law in a statewide referendum Nov. 7. The outcome of the campaign, which dominates the pre-election landscape in South Dakota, could help determine the future of abortion rights nationwide.

Supporters of the state's near-total ban on abortion hope to use it to overturn Roe vs. Wade, the 1973 Supreme Court decision that established a woman's constitutional right to terminate a pregnancy. Other states are poised to enact similar laws if this vote succeeds. If it is upheld, Planned Parenthood, which runs the only abortion clinic in the state, has said it will sue to block it in court on grounds it is unconstitutional.

"If they strike down Roe, all abortion is at risk in this country," said Eleanor "Ellie" Smeal, president of the Feminist Majority Foundation and publisher of Ms. magazine. "We estimate about 30 states would ban it."

South Dakota's law criminalizes all abortions except those "intended to prevent the death of a pregnant mother." It makes no exception for rape or incest, or for cases where the woman's health is at risk.

Dr. Marvin Buehner, an obstetrician in Rapid City, says the law would tie his hands when treating patients with serious medical complications.

Buehner recounted the case of a 38-year-old woman who was diagnosed with rectal cancer at the same time her 13-week pregnancy was confirmed. "The oncologist recommended radiation to the pelvis and immediate chemotherapy, which would have been fatal to the fetus," he said.

Buehner said the woman, whom he described as "pro-life," agonized over the dilemma but ultimately decided to abort "because she felt she had an obligation to her other children." Had the ban been in effect, Buehner said, he could have gone to jail for terminating the pregnancy.

"I would have had to prove my termination prevented her death," he said, "and I can't do that."

A small group of physicians who support the abortion ban argue that the law allows them to treat a pregnant cancer patient. The statute says medical treatment that results in the "accidental" death of a fetus is not a violation.

That makes Buehner furious. If you treated that woman's cancer without terminating the pregnancy first, he said, "you'd have a dead fetus in an irradiated pelvis in an immune system compromised by chemotherapy. So when she starts to hemorrhage from her miscarriage, emptying her uterus will be fraught with peril."

Anti-abortion forces say the other side is deliberately focusing on a handful of horrible cases rather than on the vast majority of abortions, which they claim are done for "convenience" or "birth control."

"We need to protect the lives of millions of unborn children," said state Rep. Roger Hunt, a Republican who sponsored the ban.

Andrew Johnson, a 22-year-old senior at the South Dakota School of Mines and Technology in Rapid City, said he planned to vote "Yes" on the abortion ban "for religious and moral reasons."

"Also," he said, "some supporters are women who have had abortions, and it really affected them mentally and physically." Johnson said adoption was a better alternative, "and then that child will have a chance to live."

The issue has mobilized South Dakotans who were never active before, from teenagers to octogenarians.

"This legislation has made people awaken from their complacency," said Jessica Nathanson, an assistant professor of English and gender studies at Augustana.

Last March, when Gov. Mike Rounds signed the abortion ban, "it really got me fired up," said Augustana student Judie Marshall. Marshall, 19, is working with Andert to register voters and shuttle them to the Minnehaha County Courthouse, where they can vote early with absentee ballots.

Dr. Anne Fisher, 50, an emergency physician, volunteers at the Rapid City headquarters of the South Dakota Campaign for Healthy Families, the coalition fighting to repeal the ban, known officially as Referred Law 6.

"I was never involved in a political campaign before," said Fisher, who said she's never performed an abortion and wouldn't have one herself. "But this is just incredibly important. The law is so unfair. It's worth taking a stand publicly."

The anti-abortion side is equally passionate. Church groups have been busing teenagers to the state capitol to lobby politicians. One Baptist congregation in Rapid City has had a voter-registration table at its Sunday services. And VoteYesForLife.com, the organization fighting to retain the ban, says it has "thousands" of volunteers planting lawn signs, manning phone banks and holding house parties.

Leslee Unruh, campaign manager of VoteYesForLife.com, insists the ban is essential to protect women's health, and argues that most abortions are coerced by male partners who seek to exploit women. Unruh runs a support group for "post-abortive" women, like herself, who were traumatized by the procedure.

The abortion ban so dominates the political debate in South Dakota, you'd hardly know there's a general election on Nov. 7.

"Vote Yes on 6" signs far outnumber "Rounds for Governor" signs.

"This is all the candidates are talking about, instead of worrying about education and other pressing problems," said state Sen. Stan Adelstein, a long-time legislator who — like three other moderate Republicans who voted against the ban — was beaten in the June primaries by a conservative Christian.

Adelstein, who co-chairs the Campaign for Healthy Families, is organizing four Democratic Senate campaigns.

"My party needs to get back to focusing on true Republican issues — keeping government out of people's lives, economic growth, education of gifted children and diversity of lifestyle and faith," said Adelstein, who is Jewish. "The only way to get people like me back in power is to throw the scoundrels out."

Neither side in the abortion campaign will say how much money has been raised. They acknowledge that donations are coming in from outsiders as well as from South Dakotans.

VoteYesForLife.com's pink-and-blue signs seem to be everywhere. The Campaign for Healthy Families said distribution of its lawn signs would start this weekend. But some supporters of abortion rights in South Dakota believe most people who share their views are in the closet.

"You don't see any businesses with 'Vote No' signs in their windows," said John Thies, 22, who works in a record store in Sioux Falls. "This is a conservative community. If you hold different views you're not going to advertise them for fear people will take their business elsewhere."

Nevertheless, polls Polls show the "No" side ahead. A statewide survey run by the Argus Leader newspaper and KELO-TV in late July found that 47 percent of South Dakotans were against the ban, 39 percent support it, and 14 percent were undecided. A majority of the opposed and undecided said they would support a ban that allowed exceptions for rape and incest. The ban is on hold pending the outcome of the referendum.

South Dakota allows citizens to refer legislation to the general electorate in the form of ballot initiatives.

Opponents of the abortion ban collected some 38,000 signatures — more than twice the number necessary — to put the law on the ballot in an attempt to repeal it.

"We refer anything that pisses us off," said Kevin Woster, a veteran political reporter. "This kind of citizen government is a big part of who we are."