The fight over personhood has long driven a wedge in the anti-abortion movement, but the divisions are deepening as the issue becomes a greater political liability.

Republican candidates this year face intense criticism for past support for giving full constitutional rights to a fetus, and activists are divided over whether to continue pushing the idea.

The National Right to Life Coalition, the nation’s largest anti-abortion group, has come down against pursuing personhood. This year, it cut ties with Georgia Right to Life after the state group insisted on opposing abortions even in cases of rape or incest.

A spokesman for the NLRC said personhood proposals hurt the anti-abortion cause.

“It's a dangerous and damaging distraction, that's what it is,” said James Bopp Jr., general counsel for the group. “And the vast majority of the people in the pro-life movement see it that way.”

Personhood backers disagree. They argue that groups such as the NRLC are stuck in the past.

“A lot of the people who have opposed personhood are kind of the old guard in the pro-life movement, and they have very specific ideas on how things should be done,” said Jennifer Mason, co-founder of Personhood USA. “They've had the opportunity or 40 years to end abortion, and it hasn't happened.”

Ground zero for the debate is Colorado, where one of the most hard-fought battles for the Senate is being waged this year in large part on abortion and birth control arguments.

Democratic Sen. Mark Udall has criticized Republican candidate Cory Gardner for his support for a personhood measure in 2010. Gardner tried to defuse the issue by retracting his support in March, calling personhood “a bad idea driven by good intentions.”

He’s also come out in favor of making birth control pills available without a prescription, even running a TV ad to make the case.

Personhood USA, the national group that backs personhood measures nationwide, has not minced words in response to Gardner’s change of heart on the issue.

“Personhood USA doesn't have any hard feelings, but I know Colorado voters do,” Mason told the Washington Examiner. “He's just another politician who didn't keep his word.”

Gardner is trying to avoid the fate of Ken Buck, a GOP Senate candidate who lost his bid in 2010 after criticism for his support of a personhood amendment that year.

“If Cory Gardner loses, there will be a whole lot of finger-pointing and people putting blame at the feet of the personhood movement,” said one senior-level conservative strategist who is following the race.

The concept of personhood has been around since the Supreme Court’s ruling in Roe v. Wade, and it has since come in and out of fashion within the pro-life movement. Most anti-abortion advocates have decided it is more pragmatic to attempt incremental changes, rather than tackling abortion laws wholesale through ideas like personhood.

Bopp, with the NLRC, drafted a lengthy memo making the case against personhood in 2007 which was widely circulated at the time. In it, he argued that the proposals were a waste of time and resources and would hand ammunition to the other side.

He says the Colorado Senate race has proven his theory.

“Colorado is one of few places where a significant number of people have gotten behind (personhood), and look at the result: The state has gone Democratic and rabidly pro-abortion,” Bopp said.