The “personhood” movement—which seeks to ban abortion by defining human embryos as full-fledged people with legal rights—hit a snag on Wednesday, with the Colorado secretary of state saying the group hadn’t submitted enough valid signatures to qualify for an amendment on the state ballot this fall. Keith Mason, the president of the Denver-based nonprofit group Personhood USA, vowed to fight the finding in court.

Secretary of State Scott Gessler said in a statement that officials had verified 82,246 signatures out of 106,119 signatures submitted in early August. The number required to make the ballot is 86,105, so personhood is short by 3,859 signatures.

Mason said activists had submitted more than 112,000 signatures—some 6,000 more than state officials had acknowledged. “We’re trying to get to the bottom of that now,” Mason said. He said he had talked to the secretary of state’s office and that “they were friendly, but basically said, ‘Take us to court.’” Mason said his group has hired the law firm Jackson Kelly to do so and that the group has 30 days to challenge the finding.

“We’ll be looking at every signature they threw out, fighting for every signature,” Mason said. Valid signatures from Colorado residents who are registered voters were tossed, he said, citing one example of a four-year resident who is using a California driver’s license, having lived in California before Colorado. “I know that we’ve recovered nearly 3,000 signatures already, just in a few hours,” Mason said. “I’m very confident that we have the signatures.”

A spokesman for the secretary of state said the office verifies signatures “by checking the information on the signature line against our statewide voter-registration database. A person must be registered to vote at the correct address they write on the petition for the signature to be counted as valid.” He said a state ID such as a driver's license is not required.

Personhood amendments have made it on to the Colorado ballot twice before, getting 27 percent of the vote in 2008 and 30 percent in 2010. Earlier this year, the group failed to collect enough signatures to make state ballots in Ohio and Montana initiatives, and an Oklahoma initiative was blocked by the state Supreme Court. Mason has filed a petition to appeal the Oklahoma ruling with the U.S. Supreme Court. Last year in Mississippi, a personhood amendment made the state ballot and had looked set to win, according to polling in the days before the vote; then a coalition of pro-choice groups rallied, making thousands of phone calls and ultimately swinging the vote. Personhood lost, with 42 percent.

Cecile Richards, the president of the Planned Parenthood Action Fund, said Wednesday in a statement, “The defeat of personhood state constitutional amendments all across the country—from Colorado and Ohio, to Mississippi and Oklahoma—sends a clear warning to Mitt Romney: health care decisions should be left to a woman, her family, her doctor, and her faith—not politicians. This is just one more example of how out of touch Mitt Romney is with women and the majority of Americans when it comes to women’s health. Even with personhood off the ballot in 2012, unfortunately women’s health still is very much on the ballot. The choice for women in this election couldn’t be more clear: Mitt Romney is wrong for our health and for our economic concerns.”

Pro-choice activists argue that personhood legislation would ban contraceptives and infertility treatments that can result in the destruction of embryos. Mason has said he does “not oppose contraceptives,” but methods that “kill a living human being.” In other words, he is against methods that prevent an egg from implanting in the womb after fertilization, as he believes life begins at fertilization, arguing that it's the moment when traits such as hair color and eye color are determined. The morning-after pill and copper IUD can prohibit implantation in the womb, according to the FDA, although the science behind this has been questioned. As for infertility treatments such as in-vitro fertilization, Mason has said he doesn’t think they should be banned, but “reformed” so that embryos aren’t discarded.

Rep. Diana DeGette (D-CO), the co-chairwoman of the Congressional Pro-Choice Caucus and author of the book Sex, Science, and Stem Cells: Inside the Right-Wing Assault on Reason, said she believes that defining embryos as legal people would destroy hard-won women’s rights—and potentially call into question any law that involves the word “person,” including property and inheritance laws. “These back-of-the-napkin initiatives have so many unintended consequences,” said DeGette, who has fought against personhood initiatives in Colorado in the past. “These people don’t care about science or logic.”

Abortion has dominated the headlines this month, following controversial comments from Rep. Todd Akin (R-MO) that “legitimate rape” rarely leads to pregnancy. The remarks sent Republicans scrambling to distance themselves from the congressman. The controversy also put rape and abortion in the spotlight, highlighting the beliefs of many pro-life activists and Republicans—including vice-presidential nominee Rep. Paul Ryan (R-WI)—that abortion should be banned even in the case of rape or incest.

Ryan subsequently dialed back his stance on rape and incest, saying he would support Mitt Romney’s stance that abortion should be allowed in those instances. The move infuriated many pro-lifers.

Personhood proponents believe abortion should be banned in the case of rape or incest, arguing that the fetus should not be killed for the abuser’s crime.