Millionaire Republican presidential candidate Mitt Romney admitted Friday that he wasn't sure what Medicaid was before being elected as governor of Massachusetts at the age of 55.

"Medicaid, you wonder what Medicaid is, those that are not into all this government stuff," Romney told voters at a campaign event in Sioux City, Iowa. "You know, I have to admit I didn't know all the differences between these things before I got into government."

"Then I got into it, and I understood that Medicaid is the health care program for the poor," he explained.

The candidate said that as president, he would work to turn Medicaid over to the states in a block-grant program.

"We're not going to have the federal government tell you how to care for your own people," Romney declared. "Let states craft their own program, and then grow that program at inflation plus 1 percent. If we do that, by the way, we save about a hundred billion dollars a year."

Romney's plan is similar to one offered by Rep. Paul Ryan (R-WI). Responding to Ryan's plan for Medicaid earlier this year, the Congressional Budget Office (CBO) concluded that "[t]o maintain current service levels in the Medicaid program, states would probably need to consider additional changes, such as reducing their spending on other programs or raising additional revenues."

"Alternatively, states could reduce the size of their Medicaid programs by cutting payment rates for doctors, hospitals or nursing homes; reducing the scope of benefits covered; or limiting eligibility," the CBO said.

Watch this video from CNN, broadcast Dec. 16, 2011.