Kentucky Republican Senator Rand Paul committed the biggest unforced error of his as-yet-undeclared presidential campaign on Monday, saying – in two separate interviews – that parents should be allowed to skip vaccinating their children against deadly diseases.

Paul, an ophthalmologist by training, told talk radio host Laura Ingraham that while he's not 'anti-vaccine,' most vaccines 'ought to be voluntary.'

'While I think it is a good idea to take the vaccine,' Paul said, 'I think that is a personal decision for individuals.'

Claims of a link between autism and the Measles, Mumps and Rubella vaccine were debunked years ago after the British doctor who first proposed it faked his research and lost his medical license.

Paul's moment of mixing libertarian politics with sketchy science came hours after New Jersey Gov. Chris Christie told reporters in the United Kingdom that 'parents need to have some measure of choice. ... It depends on what the vaccine is, what the disease type is and all the rest.'

'And so I didn't say I'm leaving people the option,' Christie had cautioned. 'What I'm saying is that you have to have that balance in considering parental concerns.'

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'PROFOUND MENTAL DISORDERS': Sen. Rand Paul, a Kentucky Republican on the cusp of a presidential campaign, told CNBC that parents should be permitted to opt out of vaccinating their children

New Jersey Governor Chris Christie, shown leaving 10 Downing Street after meeting British Prime Minister David Cameron, said Monday that parents should have some 'choice' in whether their children are vaccinated

'SCIENCE IS ... PRETTY INDISPUTABLE': Obama said in an interview aired Monday morning that parents should vaccinate for good health

The Democratic National Committee quickly posted an audio copy of Sen. Paul's radio interview online to embarrass him, but the Kentuckian doubled down an hour later during a television appearance.

'I have heard of many tragic cases of walking, talking normal children who wound up with profound mental disorders after vaccines,' he told CNBC host Kelly Evans.

Paul said he favored giving parents the right to stagger children's vaccine schedules so they don't get them all at once, and to opt out of preventatives against the Hepatitis B virus, which is transmitted via sexual contact, intravenous drug use and blood transfusions.

Radio host Laura Ingraham was the first to ask Rand Paul – a senator and a doctor – what he thought about vaccines

'You know, for most of our history they have been voluntary,' Paul told Evans. 'So I don't think I'm arguing for anything out of the ordinary. ... I'm not arguing vaccines are a bad idea. I think they are a good thing, but I think the parent should have some input.'

'The state doesn't own your children. Parents own the children. And it is an issue of freedom and public health.'

Paul's and Christie's timing couldn't be worse.

California and federal government public health officials are currently grappling with an outbreak of 102 cases of measles whose epicenter appears to be the Disneyland theme park.

The United States officially declared in 2000 that measles had been 'eliminated' nationwide.

While it's not clear why the highly contagious disease is making a comeback, the Centers for Disease Control and Prevention reported Monday that most of the new patients were never vaccinated.

SERMO, an online social networking website for American physicians, surveyed more than 3,000 doctors and announced Monday that 92 per cent of them believe the outbreak is 'directly attributable to parents not vaccinating their children.'

And 79 per cent of the doctors agreed that unvaccinated children should not be allowed to attend public schools unless there was a medical reason why they couldn't have a certain vaccine.

President Barack Obama created the mini political firestorm on Sunday in an interview broadcast on Monday's 'Today' show.

'I understand that there are families that in some cases are concerned about the effect of vaccinations,' he explained. 'The science is, you know, pretty indisputable. We've looked at this again and again. There is every reason to get vaccinated, but there aren't reasons to not.'

His views, however, have evolved considerably.

As a presidential candidate in April 2008, Obama told and audience in Blue Bell, Pennsylvania that 'no one knows why' America's rate of autism diagnoses had been on the rise.

'There are some people who are suspicious that it's connected to vaccines and triggers. ... The science right now is inconclusive,' he said. 'But we have to research it.'

Obama in 2008, like Paul on Monday, allowed that some vaccines have been miracle workers.

'Those vaccines are also preventing huge numbers of deaths among children and preventing debilitating illnesses like Polio,' the then-future presdient said. 'And so we can't afford to junk our vaccine system.'

Anti-vaccine warriors, led by environmental groups, had argued during the century's first decade that thimerosol, a preservative used in the Measles, Mumps and Rubella (MMR) vaccine – which is cultured in raw eggs – was the autism culprit because it contained mercury.

The biggest cheerleader for that idea was Robert F. Kennedy Jr., the lawyer-turned-green-avenger who also argued that a different, organic form of mercury was contaminating ocean fish.

VACCINE DENIER: Robert F. Kennedy Jr. pushed a controversial theory for years – that a mercury-based preservative in vaccines was giving children autism – but his most famous article on the subject, 'Deadly Immunity,' was later deleted by Salon.com and rubbished completely

HAPPIEST PLACE ON EARTH? Disneyland in Anaheim, California si the epicenter of a measles outbreak which, so far, hasn't killed anyone

Christie (right) and his wife Mary Pat (center) visited a life science company in Cambridge, England on Monday, where he waded into the global controversy over childhood vaccines

Kennedy wrote a conspiracy-minded article in 2005, published in print by Rolling Stone and online by Salon.com, in which he claimed scientists and government agencies were colluding with vaccine makers to cover up evidence of a brain-wasting epidemic.

Salon.com withdrew the article six years later and deleted it from its website, although copies have survived online elsewhere.

Kerry Lauerman, Salon's editor, wrote in 2011 that he was now engaged in the 'critical pursuit of others who continue to propagate the debunked, and dangerous, autism-vaccine link.'

As early as 2008, though, when Obama mused about 'inconclusive' science, there were already at least five large epidemiological studies establishing the lack of a connection.

And in 2004 an expert panel at the U.S. Institute of Medicine ruled 'that the body of epidemiological evidence favors rejection of a causal relationship between the MMR vaccine and autism.'

More recently, the American Academy of Pediatrics published a list of more than 40 studies demonstrating that the vaccine-autism 'link' was a hoax.

LIke Kennedy, the British physician who launched the controversy has been ostracised by mainstream and reputable scientists.

Dr Andrew Wakefield's fear-inducing study consisted of 12 children who were paid for samples of their blood. After the prestigious academic journal The Lancet withdrew the paper, he was barred from practicing medicine in the UK.

Wakefield was later found to have altered the children's medical records, and to have accepted payments from personal injury lawyers who aimed to sue vaccine manufacturers.

The White House seems to have gotten the message: On Monday Obama was unequivocal.

'You should get your kids vaccinated – it's good for them,' he told NBC's morning audience.

'We should be able to get back to the point where measles effectively is not existing in this country.'

A MOMENT OF PAIN, A LIFETIME OF SECURITY: Vaccines protect against measles, mumps, rubella, tetanus, diphtheria, Pertussis, and a host of other diseases that used to kill countless children

In addition to vaccines that prevent measles, Obama also talked with TODAY co-host Savannah Guthrie about his legacy in office, 'deflategate' and the ISIS terror army

Hours later, as Christie toured flu vaccine maker MedImmune in the United Kingdom, he was asked for a reaction.

He said he and his wife had vaccinated their children, describing that decision as 'the best expression I can give you of my opinion.'

Doing so is an 'important part of making sure we protect their health and the public health,' Christe added.

'But it's much more important, I think, what you think as a parent than what you think as a public official.'

'I also understand that parents need to have some measure of choice in things as well,' he said. 'So that's the balance that the government has to decide.'

Sensing a backlash, Christie's press office sent a statement to reporters on Monday morning insisting that he 'believes vaccines are an important public health protection and with a disease like measles there is no question kids should be vaccinated.'

'At the same time different states require different degrees of vaccination, which is why he was calling for balance in which ones government should mandate,' the statement said.

HEALTH NUT: Satellite radio host and former Playboy centerfold model Jenny McCarthy insists she's not opposed to all childhood vaccines, but her reputation as the queen of the 'anti-vax' movement is solid

Kristin Cavallari (right) believes 'there are very scary statistics out there regarding what is in vaccines and what they cause'; theories about a rise in autism diagnoses connected to childhood vaccinations have been widely debunked

All states currently require children to get certain vaccinations to enroll in school, although California and New Jersey are among 20 states that let parents opt out by obtaining personal belief waivers.

Parents in New Jersey seeking a medical exemption have to submit a written statement from their doctor or registered nurse indicating why the exemption is needed.

In thousands of cases each year across the United States, vaccinated children who are later treated with radiation for leukemia and other cancers find themselves lacking antibodies that fight off communicable diseases.

Those children can be at increased health risk if they are around others who haven't been vaccinated.

Hollywood stars including Jenny McCarthy and Kristen Cavallari have urged parents to rethink vaccines, pointing to autism as activists did a decade ago.

McCarthy now insists she's not stritcly against vaccinations – but objects to the compressed schedule along with governments recommend they be applied.

On the far opposite side of the controversy is Texas Republican Rep. Michael Burgess, a 26-year veteran of obstetrics.

He told The Hill on Monday that 'the elimination of preventable diseases has been one of biggest success stories over the past 50 years. We shouldn't discount it, because it has made a significant impact on public health.'