Republicans have fended off accusations for years that they'd gut Medicare for seniors and end the program "as we know it." 

Not Ben Carson. The former neurosurgeon acknowledges he would abolish the program altogether.

Carson, who now leads the GOP field in Iowa according to the latest Quinnipiac Poll, would eliminate the program that provides health care to 49 million senior citizens, as well as Medicaid, and replace it with a system of cradle-to-grave savings accounts which would be funded with $2,000 a year in government contributions. While rivals have been pummeled for proposing less radical changes, Carson hasn't faced the same scrutiny -- and his continued traction in polls has left GOP strategists and conservative health care wonks scratching their heads.

"This isn’t a borderline issue. The politics of this are horrific," said Doug Holtz-Eakin, head of the American Action Forum and health care adviser to Sen. John McCain's 2008 presidential campaign.

Carson's stance on the third-rail issue of Medicare is especially risky given his strength among elderly voters. In Iowa, Carson draws a quarter of the senior vote -- more than double any other candidate except Donald Trump, with whom he’s statistically tied among seniors. Carson’s support is even higher among voters between the ages of 55 and 64, who are on the verge of Medicare eligibility. He draws 34 percent of that age group, double Trump’s level of support, according to the Quinnipiac poll. 

Carson's GOP rivals are largely holding their fire so far. Trump's campaign declined to comment, as did the campaigns of Jeb Bush, Ted Cruz, Carly Fiorina and Marco Rubio. A spokeswoman for Bobby Jindal noted the Louisiana governor's support for reforming -- but preserving -- Medicare and Medicaid.

“Without change, they will go bankrupt,” said the spokeswoman, Shannon Dirmann. “Abolishing them is bad policy.”

Carson's position also puts him at odds with the Republican Party platform, which says the party “is committed to saving Medicare and Medicaid.” In a statement, the Republican National Committee chalked up Carson's position to the diverse opinions of its candidates.

Carson campaign declined requests to comment for this story.

The former neurosurgeon regularly talks up his savings account plan on the campaign trail and calls for the repeal of Obamacare, but he doesn't typically emphasize that moving dollars out of "traditional health care" means eliminating Medicare and Medicaid too.

"I have suggested that we provide the ability for anyone to have a health savings account from the day they are born until the day they die," he said during a speech at Cedarville University on Sept. 22. "We’ll pay for it with the same dollars that we pay for traditional health care with."

When pressed on his position in May by CNBC's John Harwood, Carson said Americans would support the elimination of Medicare when presented with the facts of his plan.

"When people are able to see how much more freedom they will have, and how much more flexibility they will have, and how much more choice they would have, I think it's going to be a no-brainer," he said.

Democrats and their allies have so far largely ignored Carson's position, choosing instead to highlight stray comments by Bush and Rubio criticizing Medicare. Bush continues to face criticism for his July comments suggesting he would "phase out" the program's current form. Though Bush later clarified that his comments were about reforming the program, it didn't stop Democratic frontrunner Hillary Clinton from rehashing them last week.

"I'll protect Medicare from Republicans committed to ‘phase it out,’ as one GOP candidate said,'" Clinton said in a statement marking the start of a new season of Medicare enrollment.

GOP strategists not affiliated with campaigns wonder how long Carson can avoid serious questions about his plan. Eric Fehrnstrom, who advised Mitt Romney's 2008 and 2012 presidential campaigns, pointed out that Texas Gov. Rick Perry flopped in 2012 not long after revelations that he referred to Social Security, another treasured entitlement program, as a "Ponzi scheme."

"Whether Carson can avoid Perry's fate depends on how well he explains himself, although the very act of explaining puts him at a competitive disadvantage," Fehrnstrom said. "People like their entitlements, and as expensive as they are, candidates step gingerly around how they would change them until after they are safely elected."

Conservative health care analysts who reviewed Carson's plans lauded his willingness to broach entitlement reform but cringed at the effort required to sell it.

"I would guess that the impact on Medicare would be the biggest political obstacle to this plan," said Chris Jacobs, a conservative health policy expert who's worked for Jindal and conservative former Sen. Jim DeMint, in an email. Jacobs said the fiscal trajectory of Medicare will require reforms eventually, so Carson was right to dive in headfirst. "One might as well go in for a dollar if you're going to be in for a dime," he said.

Carson's willingness to ignore long-held tropes on the political toxicity of tackling Medicare does have its advantages -- it plays into his appeal to voters frustrated with the GOP establishment and looking for a dramatic break with the status quo.

Under the plan Carson outlined most specifically last year, the government would contribute $2,000 to each individual’s tax-free account every year, with a third of the funding earmarked for insurance to cover severe medical incidents. Individuals and employers could contribute additional funds to the accounts, and the unspent funds could be shared among family members, which Carson says "makes every family their own insurance company."

His main selling points – his plan gives people control of their own health care spending and would be cheaper to administer. The plan, he estimates, would cost the federal government $630 billion annually, a back-of-the-envelope calculation of providing the $2,000 credit to an estimated 315 million Americans. 

“That’s not a whole lot compared to what we’re spending now, and everybody would have health care,” Carson said in an April 2014 video.

But that estimate doesn’t account for population growth, inflation, administrative costs, or funding a separate coverage program he's supported for the “5 percent of patients with complex pre-existing or acquired maladies.” This system would be similar to Medicare and Medicaid for the most vulnerable patients but would still incorporate “elements of personal responsibility,” he wrote in a July 2014 op-ed. 

Carson acknowledges that opponents of his plan will criticize his proposal to give the poor savings accounts rather than Medicaid, a program that provides 72 million low-income Americans with basic and long-term care services. Carson suggests that giving Medicaid members a savings account would empower them to have more control over their health care.

“People in Washington say, ‘Well, you can’t give poor people a health savings account because they’re too stupid. They won’t know what to do with it.’” Carson said at a West Des Moines, Iowa, town hall in August. “But the fact of the matter is, that is not the case.”

Carson's vision for Medicare goes much further than the premium support plan authored by Rep. Paul Ryan, which Democrats have wielded as a political weapon in the last two election cycles. Under the Ryan plan, seniors could purchase private health insurance with government help instead of getting covered directly by Medicare – which critics say would force seniors to pay more for care if private insurance costs outpace government support. Some versions of the plan would also allow seniors to stay in the traditional program, though it might cost them more. 

Republicans have largely embraced premium support as tool for taming entitlement spending -- House budgets have included the Medicare overhaul in recent years. But nothing has come to pass: the politically risky scheme was dropped from the final budget resolution approved by the GOP-controlled Congress this year.