Sarah Palin said President Obama needs to take a "do-over" on his choice for White House chief of staff, pressing Saturday for Rahm Emanuel's firing after he used the word "retarded" to lambast a group of Democrats in a strategy session last year.Emanuel is known for his coarse tongue, but the remarks touched a nerve among disability advocate groups, as well as Palin, when it was reported last week. Emanuel swiftly apologized to Special Olympics head Tim Shriver and then convened a meeting with him and other disability groups at the White House....