From the country’s heartland, voters sent messages that altered America’s culture wars and dismayed the religious right — defending abortion rights in South Dakota, endorsing stem-cell research in Missouri, and, in a national first, rejecting a same-sex marriage ban in Arizona.

Conservative leaders were jolted by the setbacks and looked for an explanation yesterday. Gay-rights and abortion-rights activists celebrated.

The verdict on abortion rights was particularly clear. Oregon and California voters defeated measures that would have required parents to be notified before a girl under 18 could get an abortion, and South Dakotans — by a margin of 56% to 44% — rejected a new state law that would have banned all abortions except to save a pregnant woman’s life.

“This was really a rebellion in the heart of red-state, pro-life America — the heart of the northern Bible Belt, “the head of the Planned Parenthood chapter that oversees South Dakota, Sarah Stoesz, said. “It sends a very strong message to the rest of the country.”

South Dakota legislators had passed the law in expectation that it would trigger a court challenge and lead to a possible Supreme Court reversal of the 1973 Roe v. Wade decision legalizing abortion. Abortion-rights leaders said yesterday that such strategies should be abandoned.

“Voters in every corner of the country made it clear they are tired of divisive attacks on a woman’s right to choose,” the president of NARAL Prochoice America, Nancy Keenan, said.

Anti-abortion leaders said the GOP shared some of the blame for the defeat. The president of Human Life International, the Reverend Thomas Euteneuer, said President Bush and other top Republicans failed to campaign strongly for the South Dakota abortion ban and against the Missouri stem-cell measure.

“While South Dakotans fought valiantly to defend their babies, we once again witnessed an almost total lack of support from the national leadership,” Mr. Euteneuer said.

The anti-abortion group Operation Rescue said the election results meant any legislation from Congress restricting abortion would be “virtually impossible” for the next two years.

“America has voted, and the bloody results have placed the most vulnerable among us, the pre-born, in the crosshairs for continued extermination,” the president of Operation Rescue, Troy Newman, said.

A conservative analyst with Concerned Women for America, Janice Shaw Crouse, suggested that Republicans — some of them entangled in corruption and sex scandals — had lost some of the selling power of the “family values” themes they had pushed in recent elections.

“Families had such high hopes when conservatives were in power; they ended up discouraged, disappointed, and disillusioned,” she said.

In Missouri, anti-abortion groups, evangelical Christian clergy, and the Roman Catholic Archdiocese of St. Louis campaigned hard against the stem-cell measure, contending it would condone life-destroying embryonic research.

A Catholic from Jefferson City, Mo., Debbie Forck was among those giving the measure a narrow victory.

“I’ve had several family members that have had debilitating illnesses,” Ms. Forck, 50, said. “It goes against my church, but to eliminate pain in my life, I thought it was worth it.”

Liberal groups did have some setbacks. Michigan voters approved a ban on some types of affirmative action programs, Colorado and Arizona passed measures targeting illegal immigrants, and seven states approved gay-marriage bans, joining 20 that had done so in previous elections.

However, gay-rights supporters took heart at the relatively close results in some of the seven states, notably in South Dakota, where the ban received only 52% of the vote.

In Arizona, the defeat of the ban stemmed in part from its scope. It not only would have reinforced an existing state law against same-sex marriage, but it also would have barred any government entities from recognizing civil unions or domestic partnerships in providing benefits to employees.

“We knew all along that once voters were informed about the true impact … they would oppose this hurtful initiative,” Steve May of Arizona Together, which opposed the measure, said. Gay-rights leaders said the election results would likely shelve any serious push for a federal ban-gay-marriage amendment. They also were pleased by the defeats of several Republicans whom they considered archenemies — notably Senator Santorum of Pennsylvania and Rep. John Hostettler of Indiana.

“It’s the end of an era for divisive, gay-bashing politics — at least in the minds of the American people,” the president of the Human Rights Campaign, Joe Solmonese, said.

Similarly, abortion-rights groups welcomed the defeat of Kansas Attorney General Phill Kline, a Republican who had touted his efforts to seize women’s medical records from abortion clinics.

“It is time to end the abortion wars,” the president of Catholics for a Free Choice, Frances Kissling, said.

One election subplot was a campaign led by New York City real-estate investor Howard Rich to promote ballot measures in numerous states seeking to rein in state and local government.

Of nine Rich-supported measures, only one succeeded — a property-rights measure in Arizona that would require state and local authorities to compensate property owners if land-use regulations lower the value of their property. Similar measures lost in California, Idaho, and Washington, while Oregon and Colorado rejected termlimit bills, and Maine, Nebraska, and Oregon rejected proposals to cap state spending.