Both New Jersey Governor Chris Christie and Kentucky Senator Rand Paul hope to individually clinch the Republican presidential nomination for 2016; but they are now both under heavy criticism for making unguarded remarks that suggest that parents are free to not vaccinate their children, thereby endanger others in the ongoing spread of measles across some US states.

Christie, who spoke Monday after making a tour of a biomedical research lab in Cambridge, England, said that he and his wife had vaccinated their children, and then added, “I also understand that parents need to have some measure of choice in things as well. So that’s the balance that the government has to decide.”

Later Monday, Paul said in a radio interview that he believed most vaccines should be voluntary. “I have heard of many tragic cases of walking, talking, normal children who wound up with profound mental disorders after vaccines,” Paul, an eye doctor, said in a subsequent interview while suggesting vaccines were “a good thing.” ”But I think the parents should have some input. The state doesn’t own your children.”

Gov. Christie’s spokesman later released a statement to clarify what the governor meant, that “with a disease like measles there is no question kids should be vaccinated.” Sen. Paul’s office also amended that while the senator’s children are all vaccinated, he surely “believes that vaccines have saved lives, and should be administered to children.”

And Hillary Clinton, the leading Democratic hopeful for party nomination in 2016 took to Twitter to take a jab at both Gov. Christie and Sen. Paul: “The science is clear: The earth is round, the sky is blue, and #vaccineswork. Let’s protect all our kids. #GrandmothersKnowBest.”

Amesh Adalja, an infectious-disease physician at the Center for Health Security at the University of Pittsburgh, stated that “When you see educated people or elected officials giving credence to things that have been completely debunked, an idea that’s been shown to be responsible for multiple measles and pertussis outbreaks in recent years, it’s very concerning.”

And GOP operative Rick Wilson said “There’s only one of two options,” Wilson said of Christie. “Either he’s so tone-deaf that he doesn’t understand why saying this is bad for him, or this is a considered political strategy. And that would be even more troubling.”

And while the American Academy of Pediatrics strongly urges parents to get their children vaccinated against measles and other childhood diseases; the New Jersey health department’s guidelines on vaccines say that objections “based on grounds which are not medical or religious in nature and which are of a philosophical, moral, secular, or more general nature continue to be unacceptable.”

Over 4,100 cases of measles have been reported in europe last year, according to the European Center for Disease Prevention and Control; and the incitement of people not to vaccinate stems from a 1998 study published by British doctor, Dr. Wakefield, in the journal Lancet, where he said he found a link between MMR vaccination and autism. His claims were debunked and discredited and even retracted by the journal, thousands of people have taken to his views and would not vaccinate their kids.

“Choosing not to vaccinate your child could also endanger the health of other children in your community,” CDC director Tom Frieden said Monday.

A leader in Iowa’s home-school advocacy network, Barb Heki, said such parents “adhere to the idea that it’s the parents’ right to make the decision on vaccinations. “More important than a candidate’s stance on vaccinations, I’m more concerned for parents’ rights to make decisions about their own children, period,” she said. “That’s paramount.”

Louise Kuo Habakus, a radio host who runs a nonprofit group opposed to state-required vaccinations, said she helped arrange a meeting between parents and Christie on the issue in 2009 and saluted him for standing up for the “rights of parents to direct the health, welfare and upbringing of their children. He’s been absolutely constant and I believe courageous and principled on this issue,” she said.