In a sign of his campaign’s confidence on the heels of a strong Iowa win, former Massachusetts governor Mitt Romney is up with a new radio ad in South Carolina taking aim not at his campaign trail rivals, but at President Obama.

The minute-long spot echoes a TV ad that Romney’s campaign has begun airing in the Palmetto State, criticizing Obama for making recess appointments on Wednesday to fill three spots on the National Labor Relations Board. The ad also hits Obama over the long-running dispute between the NLRB and Boeing, which came to a resolution last month when the NLRB dropped its case after a new four-year labor agreement was agreed to.

“You’re seeing a president adopt policies which affect our economy based not on what’s right for the American worker but instead what’s right for their politics,” Romney says in the ad. “The National Labor Relations Board, now stacked with union stooges selected by the president, says to a free enterprise like Boeing, ‘You can’t build a factory in South Carolina, because South Carolina is a right-to-work state.’ That is simply un-American. It is political payback of the worst kind. It is wrong for America, and is something that will stop under my administration.”

The dispute had been over whether the aerospace giant unlawfully retaliated against its union employees in Washington state by moving a production facility to South Carolina after a series of strikes. Even after its resolution, the case remains a hot topic on the campaign trail, particularly in South Carolina.

The White House on Thursday dismissed Romney’s new ads.

“I find it a little rich that on this and on the appointment of Richard Cordray to be the nation’s consumer watchdog, that the former governor of Massachusetts decided to take a position, in both cases, against the security and protection of working and middle-class Americans,” White House Press Secretary Jay Carney told reporters. “The president made those recess appointments to the NLRB because the NLRB did not have enough members any more to function. And it’s an agency, an independent agency, that is designed to protect workers’ rights.”

A new CNN/Time/Opinion Research poll released Friday shows Romney with a strong lead in South Carolina, which holds its primary on Jan. 21. Romney takes 37 percent in the new poll to former senator Rick Santorum’s (R-Pa.) 19 percent and former House speaker Newt Gingrich’s (R-Ga.) 18 percent.