Two former White House aides launched a pair of independent groups Friday to defend President Obama and fight the array of conservative efforts that poured money into the last elections, adopting the same tactics condemned by Obama. The move by Bill Burton, a former Obama deputy press secretary, and Sean Sweeney, who was a top aide to former chief of staff Rahm Emanuel, confirmed the sharp reversal by Democrats on the use of undisclosed political spending. Burton and Sweeney said they were moved to create the outside groups to fend off conservatives such as the billionaire Koch brothers and American...