NORTH CANTON -- Mitt Romney's campaign is staying on the offensive in the increasingly heated debate over the future of Medicare.

Speaking in Ohio today, Romney's running mate, Paul Ryan, said the battle over Medicare is "a debate we want to have" and "a debate we're going to win."

His selection last week drew immediate attention to a budget proposal he drafted that would turn Medicare into a voucher-like system for future retirees. Republicans, in turn, called attention to President Barack Obama's health care law, which is funded in part by future savings from Medicare.

Ryan told supporters today that when Obama brought up the Medicare issue yesterday, he didn't mention that he "raided $716 billion from Medicare to pay for Obamacare."

But Ryan isn't mentioning that his own budget proposal includes the same savings, which are supposed to be realized through lower payments to hospitals and doctors and by making the program more efficient.

Romney has said he would restore the Medicare cuts.

Obama argues that the changes that he has made in Medicare, including helping seniors pay less for drugs and reducing wasteful spending, will make the program stronger financially. He says the Republican proposal "ends Medicare as we know it."