Paul Ryan went on offense Tuesday in response to criticism over his Medicare plan, using an interview with Fox News coupled with a new TV ad to claim President Obama’s health care plan treats the treasured entitlement like a “piggy bank,” while the “Romney-Ryan” plan preserves it.

Ryan, in his first one-on-one interview since being named Saturday as Mitt Romney’s running mate, told Fox News on Tuesday he thinks Medicare can be a winning issue for their campaign.

“We’re the ones who are offering a plan to save Medicare, to protect Medicare, to strengthen Medicare,” Ryan said. “We’re the ones who are not raiding Medicare to pay for ObamaCare. … We’re the ones continuing the guarantee of Medicare for people in or near retirement.”