Steve Helber/AP Photo

The Obama campaign's line of attack on its Republican opponents boils down to yesterday's tweet: "Romney and Ryan want to end Medicare as we know it while giving millionaires a tax cut."

So I asked Republican strategist Mary Matalin this morning on GMA how the Romney-Ryan campaign can beat that message?

"Here's the choice George, President Obama has ended Medicare as we know it. He has taken $716 billion out of it and put 15 bureaucrats in Washington in charge of it who will be making decisions about the kind of health care seniors will receive," she told me. "We could choose that or we could choose the Romney-Ryan version where seniors choose their own health care and it is predicated on those reforms."

"And it's the only future for Medicare. We won't have a Medicare, or at least any kind of Medicare that will deliver quality care unless we reform it now," she added

Mitt Romney won't say specifically where he disagrees with Rep. Paul Ryan over Medicare reform, instead telling reporters in Miami yesterday "the items that we agree on I think outweigh any differences there may be."

The debate over Medicare became a popular Obama campaign message shortly after Romney tapped the Wisconsin Congressman. The pick certainly gave Mitt Romney a burst of energy on the stump, but a recent poll shows an underwhelming response from Americans - the lowest initial rating since Dan Quayle was the vice presidential nominee in 1988.

Matalin doesn't think the Romney campaign should worry - they "should be and are ecstatic," she said. Instead she pointed to the elections since Obama took office in 2009.

"We had a referendum on the president on every election since his election, President Obama's election, his policies have been soundly rejected most recently in the historic midterm. What this choice of Ryan, Congressman Ryan by Governor Romney indicates is this is not just going to be a campaign but a presidency of purpose and that governor Romney wants to be the president to do something," she said.

But Romney has something to fix before he can assume the presidency. Our latest ABC News/ Washington Post poll shows Romney's unfavorability rating has increased from 31% to 49% over the past year.

"You know Barack Obama has spent and is still spending…over a $100 million in a few states, three-quarters of it negative, attacking Mitt Romney," Matalin said. "Mitt Romney needs to keep doing what he is doing which is run a principled and problem solving campaign and which will portend a popular and prosperous presidency George."