Washington Post: THE COUNTRY is about to see its fiercest climate-change battle. After years of congressional inaction, President Obamas Environmental Protection Agency is applying new rules to curb greenhouse-gas emissions from cars, trucks and most controversially power plants, the biggest national emitters. Senate Minority Leader Mitch McConnell (R-Ky.) has said he will try to restrict the EPA if Republicans take over the Senate. Mr. Obamas executive actions will be an issue in the 2016 presidential campaign....