Donald Trump: 'It's Possible' Medicare Could Be Replaced by Health Savings Accounts He calls HSAs a "down-the-middle idea" that works.

 -- Donald Trump says he agrees with fellow Dr. Ben Carson, who has suggested that Health Care Savings Accounts (HSA) could render Medicare unnecessary.

"Well, it's possible," Trump told George Stephanopoulos on "This Week" Sunday.

"You're going to have to look at that, but I'll tell you what, the Health Savings Accounts, I've been talking about it also. I think it's a very good idea and it's an idea whose probably time has come," Trump said.

The Republican presidential frontrunner has echoed his closest competitor's call for reforming health care using the accounts, which would shift funds from Medicare, Medicaid, and other health care programs to individual health savings accounts.

"I'm OK with the savings accounts. I think it's a good idea; it's a very down-the-middle idea. It works. It's something that's proven," Trump said.

He added that the biggest improvement to the U.S. health care system would be to repeal and replace Obamacare.

"I don't know if you have been watching lately over the last couple of weeks -- people's premiums, George, are going up 35, 45, 55 percent," Trump said. "Their deductibles are so high nobody's ever going to get to use it."

Trump argued that Obamacare is "turning out to be a bigger disaster than anybody thought."

"Forget about the $5 billion website; that was the beginning. That was really the beginning of the end," he said. "Obamacare is a disaster."

Despite agreeing with Carson’s HSA proposal, Trump has recently amped up criticism of the retired neurosurgeon over some of his policies and positions. While Trump remains first in national polling, two new polls released last week showed Carson besting Trump in Iowa.

When asked if Carson is currently his biggest competition, Trump responded, "Well, in Iowa he is. Not everywhere else, because everywhere else I see they're all different people all over the lot, all scattered all over the place. ... In New Hampshire I have a massive lead."

Adding that Carson "got a lot of PR" from coming in first in Iowa, Trump said his runner-up standing in the early caucus state is hard to believe, given his warm reception from Iowans.

"I was in Iowa three days ago; we had such an unbelievable turnout that I find it really difficult to believe that I'm in second place," he said. "But we'll find out."