“If we don’t do something quickly, the blood of our children will be on our hands,” said Republican Representative Jason Villalba.

A measles outbreak in Ellis County last month. A surge in mumps cases in 2017 that led to the highest annual total in Texas in 23 years. Skyrocketing vaccine exemptions among kids. Public health experts warn Texas is on the precipice of a major disease outbreak, and point to the growing anti-vaccine movement in the state as the main culprit. But Texans for Vaccine Choice, which began as a group of “mad moms in minivans” and quickly grew into an influential political group, is more determined than ever to fight for what they say is their right to “medical freedom,” and unseat their enemies in the Republican primary.

“This is a human rights issue,” said Jackie Schlegel, the group’s executive director, in a Facebook Live video last month. Schlegel, who insists her group is not anti-vaccine, but rather “pro-vaccine choice,” lamented what she says is uncivil treatment from doctors and lawmakers opposed to their mission. “There is a war on women, and it starts with a war on mothers,” she said.

A single mom who says one of her kids was injured by vaccines, Schlegel started Texans for Vaccine Choice in response to a 2015 bill by state Representative Jason Villalba, R-Dallas, that would have eliminated non-medical “conscience” exemptions for vaccines at public schools. Exemptions are a matter of “liberty,” “parental choice” and “privacy,” says Schlegel, who did not respond to requests for an interview.

Villalba says he introduced the 2015 legislation because he has children in public school. Though his kids are vaccinated, he was alarmed by surging exemption rates. The number of kids with “conscience” exemptions has increased from about 2,300 when they were first allowed by the Legislature in 2003, to nearly 53,000 in 2017.

“They say this is a parental rights issue, but the right to swing your fist in America ends at my face,” Villalba told the Observer. “If we don’t do something quickly, the blood of our children will be on our hands.”

This primary cycle is a continuation of a grudge match between Villalba and the anti-vaxxers, who also campaigned against the Dallas Republican in 2016. Texans for Vaccine Choice designated his primary challenger, interior design firm owner Lisa Luby Ryan, as a “priority campaign,” and Schlegel has blockwalked with Ryan, who also picked up a batch of endorsements from other far-right groups including Empower Texans, on multiple occasions.

Another top target for Texans for Vaccine Choice is state Representative Sarah Davis, R-West University Place, one of the most vocal vaccine advocates among Republicans in the Legislature. The group endorsed Davis’ GOP primary challenger Susanna Dokupil as an “MVP,” donated $2,500 to her campaign, has blockwalked for her most weekends, and posts about her extensively on social media. Dokupil, endorsed by Governor Greg Abbott, is a lawyer and a board member of the Seasteading Institute, which aims to build floating libertarian cities in international waters.

“We’re getting all the messages that Texas is on the verge of a massive measles outbreak and no one seems to want to do anything about it.”

Ryan and Dokupil do not include their positions on vaccines on their campaign websites, but Dokupil countered Davis’ claim that she is opposed to vaccinations by saying she and her four kids are fully vaccinated. “In fact, I support removing cost barriers for parents who choose to vaccinate their children.” In a YouTube video posted by Texans for Vaccine Choice in December, Ryan says, “We believe in what you’re doing, we believe in parental choice and your cause and we will fight with you.” Neither Ryan nor Dokupil responded to requests for an interview.

“It’s really scary how impactful they are,” Davis said of Texans for Vaccine Choice. “Last session, I couldn’t even get any hearings on my pro-vaccine bills. They really have been able to bully and intimidate a lot of members. And they’ve made vaccines controversial, which makes members nervous. … It really shouldn’t be controversial.”

From July to January, Texans for Vaccine Choice’s political action committee, or PAC, has raised about $56,000 in political contributions, largely from small donors. Of the more than $60,000 the group has spent during that time period, about two-thirds has gone to its own nonprofit arm, with the remainder directed to a handful of Republican candidates, according to campaign finance data. Though the anti-vaxxers’ fundraising is modest, they are able to mobilize grassroots support for candidates through blockwalking, phone banking and online messaging. Schlegel posts daily videos on Facebook from campaign events and is shown shaking Abbott’s hand in his new ad from a rally for Dokupil in the Houston area last week.

Texans for Vaccine Choice picked the wrong race to target, said Davis, whose district includes the Texas Medical Center, the world’s largest medical complex. Peter Hotez, a leading expert on vaccines and director of the Texas Children’s Center for Vaccine Development at the center, has taken to social media to warn about Texans for Vaccine Choice, which he calls an “anti-science hate group.” It “has somehow convinced [lawmakers] this is a political issue, not a health issue,” Hotez told the Observer. “It’s very nefarious what they’re doing.”

Davis says she’s glad to talk about vaccines in her race, but is taking the involvement of Texans for Vaccine Choice seriously. “If I were to somehow lose this primary and they take credit for defeating a vaccine advocate, then their strength would grow because they would feel empowered,” she told the Observer. “And other members would probably think twice about wanting to get involved in advancing good, sound public policy dealing with vaccines. I think the ramifications are big.”

The anti-vaccine movement claimed a handful of victories last session. Bipartisan legislation to publicly disclose the number of vaccine exemptions at schools failed to pass. Most pro-vaccine bills, like Davis’ HB 107 to require an annual report on rates of HPV immunization, which protects against cervical cancer, never made it out of committee. Another measure from Davis, a breast cancer survivor, to require the HPV vaccine for foster kids also failed.

“They’re as important to me as the Flat Earth Society.”

“We’re getting all the messages that Texas is on the verge of a massive measles outbreak and no one seems to want to do anything about it,” said Hotez, who calls the state “ground zero” for the country’s anti-vaccination movement. Vaccination rates in some Texas counties now hover close to the 95 percent threshold needed for herd immunity, and exemption rates at certain schools are well into the double digits. “It’s so frustrating, it’s like the train is two miles down the track, we’re watching it coming and there’s nothing we can do to stop it.”

But Villalba — who told the Texas Tribune in 2016 he wasn’t “interested in a suicide mission on this issue” and declined to file his vaccine legislation again in 2017 as a result — now says the group is “so insignificant to my campaign … they’re as important to me as the Flat Earth Society.” Villalba acknowledges the group has a Facebook following of more than 15,000 people, but “you can make a page about dog food and get 20,000 people to like it if you’ve got good marketing,” he said.

So will Villalba file his bill to eliminate conscience exemptions next session? “I can’t give you that answer now because I have not consulted with the medical community. If the medical community and [Sarah] Davis and others are supportive, yes, that’s a yes. But I can only do it if I believe that there is support among people who really understand this issue deeply,” he said. “What will be a non-factor in my decision is Texans for Vaccine Choice. They are an insignificant ant in this discussion.”