WASHINGTON -- -- One high-profile prisoner may be out of the prison camp at Guantánamo Bay. Australian David Hicks agreed late Monday to plead guilty to lending material support to terrorism, and he is expected to be sent back to his native land to serve the remainder of his yet-to-be-determined sentence.

But as Hicks prepares to leave, a new inmate -- accused of helping to plan a deadly 2002 hotel bombing in Kenya -- arrived at the prison on the U.S. naval base on Cuba's southeastern coast, underscoring that the controversial prison for terrorism suspects will not close anytime soon.

Despite mounting pressure to close it from Congress, foreign allies and even senior members of President Bush's Cabinet, the much-criticized detention center appears destined to remain open through the rest of Bush's 22 months in office and beyond.

''I think the strategy of this administration is to just hand it over to the next administration,'' said Joanne Mariner, the director of terrorism and counterterrorism programs at New York-based Human Rights Watch.

While its population is slowly shrinking -- more detainees have left Guantánamo than the roughly 385 who remain -- the facility remains stuck in a legal morass that critics charge is of the White House's own making.

About 80 detainees have been cleared to leave, but the U.S. government has yet to persuade their native countries to take them back under the conditions it wants. Transferring the prison's population to American soil, as human rights groups advocate, could open the Bush administration's battered detainee policy to new legal challenges.

''The president made clear back in September that he would love to be able to shut it down, but, unfortunately, the circumstances do not presently permit,'' White House spokesman Tony Snow said last week.

The plea offer by Hicks late Monday was a turning point of sorts for the facility, which observed its fifth anniversary in January.

The Australian was the first of 774 men known to have passed through the prison to appear before a military tribunal, which Congress authorized last year after the Supreme Court rejected an earlier White House plan to try terrorism suspects. Hicks was accused of attending al Qaeda training camps in Afghanistan, but wasn't charged with engaging in combat against U.S. forces.

Several dozen detainees could face military commissions, although charges have been prepared against only two.

''It could take another several years to get through this,'' Mariner predicted. Human rights groups were alarmed by the announcement Monday that Abdul Malik, who has been accused of involvement in a bombing in Mombasa, Kenya, that killed 13 people, none of them Americans, had been sent to Guantánamo.

Malik, whom Kenyan authorities apparently picked up in February, is the first terrorism suspect transferred to Guantánamo since September 2004, excluding 14 ''high-value detainees'' whom Bush moved there last year from secret CIA prisons.

McClatchy Washington correspondent Renee Schoof contributed to this report.