A bill that would have ended child marriage in Idaho — which has no minimum age for couples who want to wed — died in the Statehouse this year.

Republican lawmakers, who control the Legislature, opposed it, including state Rep. Bryan Zollinger, who said it "went too far."

"Obviously, I'm against child marriage," the GOP lawmaker told NBC News. "But basically marriage is a contract between people that shouldn't require government permission."

Even as more states take action to end child marriage, concerns about government overreach, along with scant data about the extent of the problem, have driven skepticism to reform across the country. The divide has sometimes created unlikely alliances between conservative politicians and liberal-leaning groups, including the ACLU and Planned Parenthood.

In California and Louisiana, opponents of change have argued that raising the minimum marriage age is an ineffective solution since other child welfare laws already can prevent young girls from being exploited.And other states, such as Massachusetts, have raised doubts about the extent of the problem, even as experts note that survivors are often reluctant to come forward.

Idaho has the highest rate of child marriages in the U.S., according to a national report from Unchained at Last, an organization dedicated to ending the practice in the U.S. The Democratic sponsor of the Idaho legislation, which would have set the marriage age at 16, said that she thought her bill was "a modest compromise."

Rep. Bryan Zollinger details legislative proposals in Boise, Idaho, on Feb. 9, 2018. Kimberlee Kruesi / AP file

However, Idaho state Rep. Christy Zito, who voted alongside Zollinger against the measure, said she was concerned about protecting the "sanctity of family." She added that there are sufficient safeguards in state law — such as a judicial review of underage marriages — to prevent older men from exploiting young girls, an issue she said she has not seen evidence of in Idaho.

Opposition to reform in California, New Hampshire

In California, a bill to set the minimum marriage age at 18 — the state's age of consent — failed in 2017 after objections from lawmakers and liberal groups such as the state's American Civil Liberties Union. The state currently has no minimum marriage age and collects little to no data on child marriages.

The ACLU argued that the bill "unnecessarily and unduly intrudes on the fundamental rights of marriage without sufficient cause," adding that "largely banning marriage under 18, before we have evidence regarding the nature and severity of the problem, however, puts the cart before the horse."

Other groups, like Planned Parenthood and The National Center for Youth Law, a youth advocacy organization, agreed.

Cassandra Levesque, 19, at Southern New Hampshire University in Manchester on June 21, 2018. Erin Clark / Boston Globe via Getty Images file

In New Hampshire, it took Cassandra Levesque and other advocates several tries to raise the minimum marriage age to 16.

After Levesque learned that the state's minimum marriage age was 14 for boys and 13 for girls, she made the issue a focus of a Girl Scout project, compiling research, contacting her state representatives and reaching out to advocacy groups. In 2017, a bill was introduced in the state House to raise the marriage age to 16 — the state’s statutory age of consent.

“I was just trying to get as many people behind this as possible,” Levesque, now 20, told NBC News.

But a legislative maneuver killed the bill indefinitely after state GOP Rep. David Bates and others raised concerns about whether teens could marry while one was deployed for military service. Bates lambasted Levesque and scolded his colleagues in a speech on the state House floor at the time.

“We’re asking the Legislature to repeal a law that’s been on the books for over a century, that’s been working without difficulty, on the basis of a request from a minor doing a Girl Scout project,” he said.

Despite the opposition Levesque faced, she was able to work with representatives to draft a new bill setting the age limit at 16, which later passed. And last year, at age 19, she decided more needed to be done on the issue and ran for a House seat in the state. She won and is now working to raise the minimum marriage age to 18.

“This time, I had all my bases covered,” Levesque said. “It’s definitely a big issue I’m trying to fight.”

Louisiana's compromise

Idaho and California are not alone in not having a minimum marriage age. A majority of states, which issue marriage licenses, allow 16- and 17-year-olds to marry, a few allow 14-year-olds, and 13 states have no minimum marriage age as of September. Before 2016 — when Virginia became the first state to put its marriage age into law — more than half of the states had no minimum marriage age fixed by statute.

Fraidy Reiss, a survivor of forced marriage and the founder of Unchained at Last, told NBC News that she finds some of the rationales against raising the minimum marriage age in all states to 18 baffling because the federal government considers marriage under 18 in foreign countries a human rights abuse.

According to the group, nearly a quarter of a million children were married in the U.S. from 2000 to 2010 — the majority of whom were young girls marrying older men.

"This is happening, and it's happening at an alarming rate," she said.

In Louisiana, a heated debate erupted in the Legislature this year as lawmakers haggled over whether to set a minimum marriage age in the state. Republicans — and a handful of Democrats — argued that teens should be allowed to marry in certain instances, such as pregnancy or military service.

“If they’re both 16 years old, and they both consent to sexual relations, and they’re about to have a baby, why wouldn’t we want them to be married?” state Rep. Nancy Landry, a Republican, said at the time.

Kathleen Benfield, the legislative director for the Louisiana Family Forum, an influential conservative nonprofit in the state, said that her organization was also concerned about forcing a teen mother to give birth out of wedlock if the age was set at 18 with no exceptions.

“We would oppose any exploitation of young girls by older men — that's the bottom line,” Benfield said. “But we just wanted to make sure that the value of marriage as a cherished institution was supported.”

In the end, the group gave the bill lukewarm support thanks to provisions such as requiring that the age difference between a minor and an adult be no more than three years, placing stringent guidelines for judges to review each case and mandating the collection of marriage data in the state to study the extent of child marriage.

The bill passed in June, setting the minimum marriage age at 16, and the law was set to take effect in August.

Roadblocks for activists

Reiss, who lobbies lawmakers as part of her group's advocacy work against child and forced marriage, said she has seen some success in direct outreach.

"Where we have less luck is legislators who say: 'I don't care. I don't care. A girl gets pregnant, she's got to get married,'" she added. "Or the ones who look at me and say — I've had this in multiple states — 'Well, Joseph married Mary when she was 8. If it was good enough for God, why shouldn't it be good enough for us?'"

She believes lawmakers often conflate the maturity of some teens with the legal capacity to enter a marriage, which is considered a legal contract that many laws specify only adults can enter into or annul.

"For someone to say if you're 17 and you're mature and in love that it's somehow OK for you to marry. No, it's not because you're still not an adult," she said. “You cannot be allowed to marry before you were allowed to file for divorce. That's just so obvious."