Gov. Sarah Palin has lost control of her public image, several top-level McCain advisers said this weekend, and even a baseline performance in Thursday's debate with Joe Biden may be too late to recover it. The decision to sequester Palin from the national political press corps was made with the assumption that the afterglow from her convention speech would last; a month later, even some Republicans are beginning to have a less favorable opinion of her. Her knowledge of policy has seemed at times no more than inch deep, and even admirers have complained that her penchant for returning to...