Volunteers of U.S. President Barack Obama election office make telephone calls to voters to urge them to support Barack Obama in Manchester, New Hampshire, the U.S., on Jan. 10, 2012. A week after the Iowa caucuses which ended up in a virtual tie at the top between Mitt Romney and Rick Santorum, U.S. Republican presidential hopefuls kick off their second contest in New Hampshire on Tuesday. [Xinhua/Fang Zhe]