Former Sen. Rick Santorum was back on the stump in his home territory of western Pennsylvania over the weekend, but this time in a new role: Mitt Romney's attack dog. "The republic is at stake," Santorum told a crowd gathered in the hot and cramped Victory Center, many of them wiping their brows. "One man is who we have to put our trust in to go out and fight that battle, and win that battle. And we must rally behind and do everything we possibly can to support Gov. Mitt Romney so he's the next president of the United States."...