Rick Santorum is looking to distinguish himself from his GOP rivals, particularly Mitt Romney, on taxes: If there’s any doubt that insurgent GOP presidential candidate Rick Santorum is gunning for the mantle of blue-collar conservative, just take a gander at his tax plan: Families with children would receive triple the current tax exemption, and companies that manufacture goods in America would not be taxed at all.The populist proposals, which set him apart from his rivals, are key components of Santorum’s “faith, family and freedom” agenda that resonated in Iowa and which he now hopes will draw blue-collar voter support in...