Abortion opponents say they're still pursuing life-at-fertilization ballot initiatives in six other states even though voters in the Bible Belt state of Mississippi rejected the conservative measure.
Abortion rights supporters praised the vote, saying the measure went too far because it would have made common forms of birth control illegal and would have forced women to carry unwanted pregnancies to term.
The White House called it a victory for women and families.
"The president believes that extreme amendments like this would do real damage to a woman's constitutional right to make her own health care decisions, including some very personal decisions on contraception and family planning," President Barack Obama's spokesman Jay Carney said in a statement.
If it had passed, the "personhood" proposal was intended to prompt a legal challenge to Roe v. Wade, the 1973 Supreme Court decision that established a legal right to abortion. A Colorado-based group, Personhood USA, is trying to get the measure on 2012 ballots in Florida, Montana, Ohio, Oregon, Nevada and California.
Voters in Colorado have already rejected similar proposals in 2008 and 2010. Keith Mason, a co-founder of the group, said they might try again in Mississippi, too.
"It's not because the people are not pro-life," Mason said of the failed ballot measure. "It's because Planned Parenthood put a lot of misconceptions and lies in front of folks and created a lot of confusion."
Planned Parenthood Federation of America said in a statement that Mississippi voters rejected the amendment because they understood it was government going too far.
The measure "would have allowed government to have control over personal decisions that should be left up to a woman, her family, her doctor and her faith, including keeping a woman with a life-threatening pregnancy from getting the care she needs, and criminalizing everything from abortion to common forms of birth control such as the pill and the IUD (the intrauterine device)."
The so-called personhood initiative was rejected by more than 55 percent of Mississippi voters, falling far short of the threshold needed for it to be enacted.
The measure divided the medical and religious communities and caused some of the most ardent abortion opponents, including Republican Gov. Haley Barbour, to waver with their support.
Opponents said the measure would have made birth control, such as the morning-after pill or the intrauterine device, illegal. More specifically, the ballot measure called for abortion to be prohibited "from the moment of fertilization" — wording that opponents suggested would have deterred physicians from performing in vitro fertilization because they would fear criminal charges if an embryo doesn't survive.
Opponents also said supporters were trying to impose their religious beliefs on others by forcing women to carry unwanted pregnancies, including those caused by rape or incest.
Amy Brunson voted against the measure, in part because she has been raped. She also has friends and family that had children through in vitro fertilization and she was worried this would end that process.
"The lines are so unclear on what may or may not happen. I think there are circumstances beyond everybody's control that can't be regulated through an amendment," said Brunson, a 36-year-old dog trainer and theater production assistant from Jackson.
Buddy Hairston, 39, took his 8-year-old triplets to a precinct outside Jackson to hold signs supporting the initiative.
"Unborn children are being killed on a daily basis in our state and country, and it's urgent that we protect them," said Hairston, a forestry consultant.
Mississippi already has tough abortion regulations and only one clinic where the procedures are performed, making it a fitting venue for a national movement to get abortion bans into state constitutions.
The state's largest Christian denomination, the Mississippi Baptist Convention, backed the proposal through its lobbying arm, the Christian Action Commission.
"We mourn with heaven tonight over the loss of Initiative 26, which would have provided the hope of life for thousands of God's unborn babies in Mississippi," said the commission's director, the Rev. Jimmy Porter. "Instead the unborn in Mississippi will continue to be led down on a path of destruction to horrible deaths both inside their mothers and in laboratories."
The bishop of the Episcopal Diocese of Mississippi and the Mississippi bishop of the United Methodist Church opposed the initiative.
Bishop Joseph Latino of the Catholic Diocese of Jackson, a church traditionally against abortion, issued a statement neither supporting nor opposing the initiative. The Mississippi State Medical Association took a similar step, while other medical groups opposed it.