After Sen. Barack Obama’s third major primary loss and endless media coverage dedicated to dissecting the apparent weaknesses of his candidacy, one of the most striking elements of his campaign this week was what’s missing: any hint of internal upheaval. At Obama headquarters in Chicago, hundreds of miles removed from the Beltway bubble, advisers held steadfast in their adherence to The Plan, a blueprint devised 15 months ago by the same inner circle that runs the campaign today, supported by the candidate and carried out by a tight-knit staff. Sen. Hillary Rodham Clinton’s operation could not be more dissimilar. Her...