A staff member is silhouetted on a poster of dropped-out U.S. Republican presidential candidate Herman Cain at his closing campaign headquarters in Urbandale, Iowa, the United States, Dec. 31, 2011. As the first contest for U.S. Republican Party to nominate their presidential candidate draws near, GOP hopefuls and their army of volunteers began their final dash Saturday towards the caucuses next week in Iowa, foregoing the New Year's Holidays. [Xinhua/Zhang Jun]