The main reason is because Massachusetts has strict minimum coverage requirements, which makes the plans more expensive in the state than anywhere else, Romney explained, adding that he tried to veto the standard of the "gold-plated plans."

Because of those mandates, the state's "health insurance was the most expensive in the nation, and still is," Romney noted. When Romneycare was passed in 2006, "nothing changed for 93 percent of our population. We were already paying for those plans," he said.

Massachusetts holds the distinction of having the lowest uninsured rate in the country. The rate hovers around 3 percent; the country's is about 14 percent.

Romney, whose plan the Obama administration has said is the basis for the Patient Protection and Affordable Care Act, distanced himself from the federal health care law, slamming crushing premiums under the law and the broken promise that consumers could keep their health plan "if they liked it."

"When you demand that everyone had gold plated plans, premiums will go through the roof. The real reason ... is because people are being forced to pay for plans that looks like Massachusetts insurance plans."

His big worry for the country's health care system is that lawmakers will push for a single payer system now that Obamacare is causing those side effects.

"I think people are still trying to push for that," he said.