Roadblocks include a congressional prohibition against transferring detainees to the United States and continuing difficulty finding countries willing to accept men who were once labeled "the worst of the worst."
In addition, Congress and the White House are working on more changes to the controversial on again, off again military commission process to try the detainees.
With many hurdles and no breakthroughs on the horizon, analysts now question whether the prison camp can close on time.
"It is very easy to say you'd like to close Guantánamo; it is hard to actually get it done," says Matthew Waxman, a Columbia Law School professor and former deputy assistant defense secretary for detainee affairs in the Bush administration. "I am skeptical – at least as of now - that the Obama administration will be able to meet its own deadline."
In his first major act as president, Mr. Obama ordered Guantánamo closed by January 2010. But with six months left in the year-long transition, officials appear still undecided on basic aspects of the closure.
For example, the Pentagon's general counsel was unable to say during recent Senate testimony whether military commission trials would be conducted at Guantánamo or somewhere else after the January deadline.
Jeh Johnson, the Pentagon's top lawyer, was asked how the administration planned to "process" the 229 detainees at Guantánamo through trials or other procedures by year's end.
"You are correct; you can't prosecute some significant subset of 229 people before January," Mr. Johnson testified. "Those that we think are prosecutable and should be detained, we will continue to detain, whether it's at Guantánamo or someplace else."
Congress has asked the administration for a detailed closure plan, and last month lawmakers set that requirement into law. A presidential task force is expected to issue a report on the closure later in July.
The task force is assessing the security threat posed by each detainee and gauging which detainees are suited for transfer to other countries, which of them can be placed on trial in federal court in the US, and which will be prosecuted by a military commission. In addition, the administration acknowledges that some detainees will continue to be held indefinitely without charge as enemy belligerents after being deemed by the Obama administration as too dangerous to release.
In his Senate testimony, Johnson said detainee assessments would be completed before the end of the year.
Although the Guantánamo closure has encountered hurdles, there has been some progress. In June, three detainees were sent to Saudi Arabia, one was sent to Iraq, one to Chad, and four Uighurs were flown to Bermuda for resettlement. In addition, Italy has agreed to take three detainees, and talks are continuing with Palau in the South Pacific to resettle some of the 13 remaining Uighurs at Guantánamo.
On the prosecution front, one detainee, Ahmed Ghailani, has been transferred to New York for trial in federal court on charges of involvement in the Al Qaeda bombing of US Embassies in Kenya and Tanzania in 1998.
Some administration officials insist the closure deadline can be met. They point to statements by the European Union of a willingness to consider accepting detainees.
Talks with allies in Europe suffered a setback when Congress barred the administration from bringing detainees to the US other than for prosecution. The move undercut US credibility in asking its allies to help close Guantánamo when the US itself is unwilling to accept detainees.
"It is not just that Congress has acted. This is a policy statement from the legislature that is directly at odds with the president's policy for [Guantánamo's] closure," says Laurel Fletcher, director of the International Human Rights Law Clinic and a professor at the University of California Berkeley School of Law.
The military prison camp at Guantánamo became a lightning rod for domestic and international criticism of the Bush administration's aggressive approach to the war on terror. It also became a recruiting tool for Al Qaeda. Obama campaigned on promises to close the prison camp and shift US policy.
But the window for quick, decisive change may be closing, analysts say.
"There was a hope that the new administration would be riding a wave of diplomatic goodwill that would energize this process of finding resettlement opportunities abroad, and in some cases they have, but it has been very slow and halting," says Mr. Waxman.
Many of Obama's core supporters are disappointed by his willingness to embrace Bush-era antiterror policies such as preventive detention, expansive invocation of the state secrets privilege, and use of military commissions.
"Across the board, it is as though the defense and intelligence communities have completely captured the administration," says David Remes, legal director of Appeal for Justice, a Washington group that represents 18 Guantánamo detainees. "The men at Guantánamo don't believe that the prison is going to close by January," he says. "Everything that has happened since Obama issued the executive order has pointed in the other direction."
Although it helped Obama win the election, closing Guantánamo is not a popular position in the US today. Forty-nine percent of voters polled in late May said they oppose it, while 38 percent favor closure.
The poll also showed that in November, 49 percent of voters said they believed Obama was very likely to close Guantánamo within a year. By late May, that number had dropped to 15 percent.
The administration has been outmaneuvered in recent months by Republicans, including former Vice President Dick Cheney. Mr. Cheney delivered a blunt warning: Closing Guantánamo would endanger the US. The underlying message: Democrats are soft on terrorism.
Congressional Democrats, with a wary eye toward midterm elections, responded by thwarting Obama on Guantánamo.
The ball is now in Obama's court, analysts say. "It boils down to political will on the White House's front," says Charles "Cully" Stimson, a former deputy assistant defense secretary for detainee affairs in the Bush administration who is now at the Heritage Foundation in Washington.
"If the president does not go all in, if he goes with half measures, he will fail," Mr. Stimson says. "But I think his instincts are to win and succeed in this."
There is one area ripe for a breakthrough that would speed Guantánamo's closure, analysts say. Of the 229 remaining detainees, 97 are from one country: Yemen. Negotiations are under way for possible transfers, but US officials are worried about security procedures in Yemen.
"Yemen is quickly becoming a failed state, and the US can't have any confidence in the security of the country," says Mr. Remes. Sixteen of his 18 clients are Yemeni.
There had been hope that Yemen might develop its own version of the rehabilitation program that exists in Saudi Arabia, where former Guantánamo detainees are provided jobs, counseling, even help finding wives. One proposal is to route those Yemeni detainees with tribal connections to Saudi Arabia through the Saudi program. But Remes says that involves 12 to 15 of the Yemenis at most.
This story appeared in print on July 19. Read an updated version of this story here.