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.