The whole party is backing away from that claim. Don’t know why but it’s just not her. Give her some slack.
She still could have said “Marxist background and history, why don’t you ask him if he still clings to the failed policies of Mugabe, Obadinga, Castro, Chavez, etc.?”
I suspect the RNC has done some polling that confirms that the average American is pretty stupid and does not know the difference between a socialist and a person who is social or has a social conscience. McCain, Palin, Romney, and others have are now avoiding the word "socialists" so as not to confuse the electorate.