Warren, who is closely aligned with progressive union groups, ripped Walker in a tweet Saturday for what some saw as a comparison between union members and the Islamic State of Iraq and Syria: "If Scott Walker sees 100,000 teachers & firefighters as his enemies, maybe it's time we take a closer look at his friends.” In a speech at the Conservative Political Action Conference on Thursday, Walker said, “If I can take on 100,000 protestors, I can do the same across the world.” Walker, a possible 2016 presidential candidate for the GOP, tried to walk back his comments after his...