The Romney campaign is pushing back hard against accusations that Paul Ryan, and by extension Romney himself, are threatening Medicare. And they're recycling an old, discredited attack line to do it.

The real assault on Medicare, according to Romney and his allies, comes from President Obama, because the Affordable Care Act calls for $700 billion in cuts to Medicare over the next decade. Here's Republican National Committee Chairman Reince Priebus making that argument on NBC's "Meet the Press" this morning:

He stole $700 billion from Medicare to fund Obamacare. If any person in this entire debate has blood on their hands in regard to Medicare, it's Barack Obama. He's the one that's destroying Medicare.

Capturing the cynicism on display here isn't easy. I'm going to try anyway.

Yes, the Affordable Care Act includes substantial cuts to Medicare. But Ryan's own budget, which nearly every House Republican voted to pass and which Romney has said he would sign as president, leaves those cuts in place and uses them to finance other priorities. In other words, the Romney campaign is attacking a proposal that Romney and his allies endorse.

The most significant difference between the two sides, at least for the short- to medium-term, is how they handle the savings these cuts generate. Obamacare puts the money back into the pockets of people who need help with their medical bills. A portion of the money is earmarked for children and non-elderly Americans, who, starting in 2014, will become eligible for Medicaid or receive tax credits to offset the cost of private insurance. A smaller, but still significant, portion of the money is for seniors. It helps them pay for prescription drugs, by filling the "donut hole" in Medicare Par D coverage. It also eliminates out-of-pocket costs for annual wellness visits, some cancer screenings, and other preventative services. Those benefits have actually started already: In the first six months of this year, according to the Department of Health and Human Services, more than 16 million seniors took advantage of the free preventative care provision.