Campaign aides to Barack Obama watched with glee in late November when a Fox News anchor confronted Mitt Romney with a Democratic attack ad. Sitting in a Florida juice factory, the tight-lipped Romney forced a smile. "I'm glad that the Democratic ads are breaking through and you guys at Fox are seeing them," he said, not looking glad at all.
Fox News wasn't the only outlet echoing the Democratic National Committee spot, called "Mitt v. Mitt," which charged Romney with flip-flopping on key issues. For much of that week, the 30-second video, accompanied by a longer online version, dominated the political...