Democratic strategists worry, however, that he may be unable to broaden his appeal -- or that he will lose his core supporters if he moves to the Clintonian center.

• 但民主党的竞选战略家担心他可能无法扩展他的魅力---或者，如果他向克林顿派系的中间立场靠拢，就会失去核心的支持者。