Mr. Obama has repeatedly said he wants to close the camp. But in an interview on Sunday on ABC, he indicated that the process could take time, saying, “It is more difficult than I think a lot of people realize.” Closing it within the first 100 days of his administration, he said, would be “a challenge.”

The president-elect drew criticism from some human rights groups Monday who said his remarks suggested that closing Guantánamo was not among the new administration’s highest priorities. But even if the detention camp remains open for months, the decision to address Guantánamo on the day after his inauguration seemed intended to make a symbolic break with some of the most controversial policies of the Bush administration.

Several national security and legal analysts have argued in recent weeks that Mr. Obama is in a delicate political position after having committed himself to closing the prison. Sarah Mendelson, the author of a report for the Center for Strategic and International Studies on how to close the prison, said Mr. Obama’s remarks on Sunday appeared intended to indicate the difficulty of the task, which she said it could take a year to complete.

“I thought he was trying to manage expectations of how quickly those detainees who remain can be sorted into two categories: those who will be released and those who will be prosecuted,” Ms. Mendelson said.

Aside from analyzing intelligence and legal filings on each of the remaining detainees, diplomats and legal experts have said the new administration will need to begin an extensive new international effort to resettle as many as 150 or more of the remaining men. Portugal and other European countries have recently broken a long diplomatic standoff, saying they would work with the new administration and might accept some detainees who cannot be sent to their home countries because of concerns about their potential treatment.