Obama hits Romney on Medicare, '47 percent'

It goes on to criticize Romney's Medicare plan, under which seniors would receive a fixed payment to help buy insurance on their own, either from a private insurer or the existing Medicare program.

In an e-mail, Romney spokesperson Amanda Henneberg said, “President Obama is the only candidate in this race who has robbed $716 billion from Medicare to pay for Obamacare. President Obama has not done anything to reform Medicare for the long haul and prevent it from going bankrupt. Mitt Romney has a plan to protect Medicare for today’s seniors and preserve and strengthen it for future retirees.”

Democrats call the plan a "voucher" system, and say it could require seniors to pay more out of pocket if they want to receive traditional Medicare.

"You're no victim. You earned your benefits. Don't let Mitt Romney take them away," the ad says.

The spot cites AARP's criticism of the Romney plan — which AARP has asked the Obama campaign to stop doing.

--This report was originally posted at 5:03 p.m. and last updated at 9:06 p.m.