Although Obama administration officials now acknowledge they're unlikely to meet the self-imposed deadline to close Guantanamo Bay, Attorney General Eric Holder insists setting a deadline was the "wise" thing to do.

"It's going to be difficult for us to make the Jan. 22 deadline," Holder told a group of reporters on Tuesday. "But I do think that it was the right thing to set that deadline. ... [It] has a way of focusing people's efforts, their attention, and giving people a goal."

Two days after taking office, President Obama signed an executive order calling for "the detention facilities at Guantánamo ... [to] be closed as soon as practicable, and no later than 1 year from the date of this order." As of two months ago, the White House was publicly sticking to its promise, despite concerns being expressed privately among administration officials.

That has changed, as top administration officials say publicly they will likely miss the deadline -- and try to recast the importance of a deadline.

"We're not focused on whether or not the deadline will or won't be met on a particular day," White House spokesman Robert Gibbs said last week. "We're focused on ensuring that the facility is closed, and doing all that has to be done between now and the 22nd of January to make the most progress that we can that's possible."

Officials haven't gone into many specifics about what's slowed them down, but Holder said Tuesday one issue has been identifying nations willing to take some detainees.

"There are a number of factors that make the planned closing date of Jan. 22 difficult," said Holder, who is leading the review of detainees' cases.

He also expressed concerns that last week's move by lawmakers opposing the transfer of any detainees to the United States could further complicate efforts to close Guantanamo Bay.

Holder suggested he may have to go to Capitol Hill to "make them understand that we have the capacity" to safely detain terror suspects on American soil.

As for why he supports the decision to set a deadline in the first place, Holder alluded to the ways of Washington.

"When you try to move bureaucraries, I think that setting specific dates makes sense," he said. "And i think it was the wise thing to do here, and led to the progress that we have made."

Of the 241 detainees who were detained at Guantanamo Bay when President Obama took office, 223 are still there.

Of the 18 no longer there, 16 were transferred to other countries, one committed suicide, and one was brought to New York to face criminal charges related to the 1998 bombings of U.S. embassies in Africa.

But, Holder said, the task force reviewing detainee cases has now "gone through all of the files."

Roughly 90 have been approved for transfer to other countries, and about 40 have been referred for prosecution, either in military commissions or U.S. federal courts, a source with knowledge of the review said.

"A number of files are being reviewed by prosecutors from four or five U.S. Attorneys' offices to see whether or not the cases are suitable for prosecution in federal courts," Holder said. That process should be done by mid-November, he said.

The nearly 100 other detainees are undergoing a "second-stage review" to determine whether they should be transferred, prosecuted by the United States, or face some other fate, the source said. That "second-stage review" should also be completed by mid-November, according to the source.

In any event, Holder said, "Guantanamo will be closed, and I think that that is an appropriate thing to do, given the fact that it has served and I think continues to serve as a recruiting for those who intend to do this nation hard, and has served as a wedge between us and those nations that are our allies."

And, he said, he's not quite ready to give up altogether on the Jan. 22 deadline.

It may be "difficult" to meet, but that "doesn't mean we're not going to try to do it," he said.