South Dakota is suddenly in the vanguard of the movement to overturn Roe v. Wade. But in truth, it was a role that was decades in the making.

Since the 1973 Supreme Court decision establishing the right to an abortion, the state Legislature has become increasingly dominated by lawmakers from both parties promoting what they see as traditional family values. In fact, in the 1990s, South Dakota's Democrats dropped abortion rights from their party platform.

The conservative shift culminated last week in passage of a bill to outlaw nearly all abortions — a measure aimed ultimately at getting Roe v. Wade overturned.

The ban sailed through the House and Senate, and Republican Gov. Mike Rounds has said he is inclined to sign the measure, which would make it a crime for doctors to perform an abortion unless necessary to save the woman's life. The bill would make no exception in cases of rape or incest.

The vote came at a time when some activists believe the high court may be more willing than ever to abandon Roe v. Wade now that conservatives John Roberts and Samuel Alito are on the bench and 85-year-old John Paul Stevens might be close to retiring.

Anti-abortion activist Leslee Unruh of Sioux Falls said support for the proposal began gathering long before Roberts and Alito were nominated. She said the issue took on urgency in recent months because term limits will soon force some key lawmakers from office.

"I know the inner workings of the Legislature and the personalities, and I know it had to be this year," said Unruh, founder of a pregnancy counseling center and an organization devoted to teaching abstinence to teenagers. "There's a window of time and this is it."

For the most part, Republicans have dominated the Statehouse since the 1970s. The last Democratic governor left office in 1978, and Republicans enjoy a 51-19 majority in the House and a 25-10 advantage in the Senate.

South Dakota, which ranks 46th in population with about 780,000 residents, has just one abortion clinic, and it performs about 800 abortions a year. Planned Parenthood, which operates the clinic, has said it will sue over the bill.

"At one time, the Legislature was pretty evenly divided between Republicans and Democrats," said Thelma Underberg, executive director of National Abortion Rights Action League Pro-choice South Dakota. "But through redistricting, they managed to get rid of a number of women ... (who) were progressive."

Underberg was on a state Democratic convention committee in 1992 when abortion rights were removed from the platform. "That was the beginning of the turning point," she said. "When you've been whipped at every turn, you want to quit."

Bob Burns, a political science professor at South Dakota State University, said that before Roe v. Wade, state politics could best be described as a moderate form of fiscal conservatism. But after the Supreme Court decision, he said, the Christian right was activated.

Unruh said national anti-abortion groups had nothing to do with passage of the bill. In fact, she said she discouraged them from lobbying because "I didn't want any of the radicals, the extremists. I didn't want trucks with pictures of dead babies driving around."

Another factor that may have contributed to the bill's passage was Democratic Sen. Tom Daschle's stinging loss to Republican John Thune in 2004. That demonstrated the clout of the Christian right in South Dakota, said Elizabeth T. Smith, a professor of political science at the University of South Dakota.

"I think legislators pay attention to those things," she said. "That may help account for the lopsided votes in favor of the ban. And when you add in the more conservative cast to the Supreme Court, it took on a new level of momentum that it hadn't before."