By comparison, Bill Clinton had filled only one of those jobs by this point in his transition, and Jimmy Carter and Ronald Reagan only two. Even the elder George Bush, who had the advantage of succeeding a fellow Republican, had picked just eight a month after his election. George W. Bush, stalled by the Florida recount, had named a chief of staff at this point in 2000 but was waiting to find out if he would even become president.

Mr. Obama’s advisers are acutely aware that moving too quickly can cause mistakes. But accounts of the process emerging from participants suggest that the president-elect is trying to be decisive as well as methodical and secretive in filling out his administration, perhaps foreshadowing how he intends to run the government.

“You don’t have time to waste,” said Rahm Emanuel, the incoming White House chief of staff, who was named to his post two days after the election. “This is the worst economic situation since the Great Depression and the largest commitment of troops overseas since Richard Nixon. That’s the world we’re inheriting, and the president-elect said we don’t have a moment to waste putting things together.”

Aides said Mr. Obama had been determined to expedite the cumbersome selection and vetting cycle that had bogged down previous transitions, in the hope that Senate confirmation of top nominees would be accelerated. They said he had been particularly committed to avoid what happened in 2001, when many top national security positions were still unfilled at the time of the Sept. 11 attacks.

So far, none of Mr. Obama’s appointees have run into serious controversies, although questions are being raised about the involvement of Eric H. Holder Jr., the choice for attorney general, in Mr. Clinton’s last-minute pardon of Marc Rich, the fugitive financier. In other cases, Mr. Obama avoided difficulty by passing over early front-runners, among them John O. Brennan, a candidate for director of the Central Intelligence Agency, who could have run into trouble.