The 2012 ad wars have officially begun.

In what appears to be the first major media buy of the 2012 presidential campaign, an independent group supporting President Obama launched television ads in South Carolina on Friday attacking potential GOP candidate Mitt Romney over health care.

Priorities USA Action, a so-called “super PAC” co-founded by former White House aides Bill Burton and Sean Sweeney, is running the ad to coincide with a Romney visit to the crucial GOP primary state.

The ad attempts to tie Romney to a House Republican proposal to replace Medicare with a voucher system, a theme that appears likely to dominate Democratic messaging for the 2012 cycle. The spot also takes aim at a Romney ally, South Carolina Gov. Nikki Haley (R), who attacked presidential candidate Newt Gingrich for criticizing the Ryan plan.

“Mitt Romney says he’s ‘on the same page’ as Paul Ryan, who wrote the plan to essentially end Medicare,” a narrator says in the ad, which features flip-flopping images of the former Massachusetts governor. “But with Mitt Romney, you have to wonder: Which page is he on today?”

The Romney campaign called the ad “a smear campaign” orchestrated by Obama’s reelection operation.

“President Obama’s first campaign ad is an attack ad,” Romney spokeswoman Andrea Saul said in a statement. “President Obama and his team are desperate to change the subject to anything other than jobs and the millions of Americans out of work. With 9.6 percent unemployment in South Carolina, voters are looking for a jobs plan not a smear campaign.”

The ad buy is notably early even for a presidential race, especially given that Romney has yet to formally launch a campaign. The move underscores the prominent role of new independent groups like Priorities USA, which is taking advantage of recent court rulings to raise unlimited funds for pro-Obama advertising and other efforts.

The group declined to say how much money it was planning to spend on the ad, which is slated to run on South Carolina stations through the weekend.