Under the direction of John Podesta, a former White House chief of staff under Bill Clinton, the transition effort includes a dozen separate groups divided into different areas of responsibility, these officials said. One added that Cassandra Butts, a longtime associate of Obama, is in charge of the group dedicated to personnel for a new administration.

The effort is largely separate from the campaign structure that helped plan and execute Obama's remarkable rise to the position of front-runner in a race in which he is bidding to become the first black president.

The officials spoke on condition of anonymity, saying they were not authorized to discuss any post-election planning that might be under way.