Several of President Barack Obama’s leading GOP critics on Wednesday seized on reports that Pentagon officials believe replacing the prison at Guantánamo Bay, Cuba, with one in the United States could cost more than half a billion dollars.

The emerging price tag could complicate Obama’s ever-difficult task of shuttering the prison, known as Gitmo, before he leaves office — one of the first goals he set upon his inauguration in 2009, but one that Congress has repeatedly thwarted.

The Obama administration needs to go “back to the drawing board” as it plans a way to close Gitmo, Senate Armed Services Chairman John McCain, R-Ariz., told reporters Wednesday.

“I still believe — and I know this is very unpopular with some of my conservative colleagues — that Guantanamo is a symbol to many in the Arab world of Abu Ghraib, of torture, of waterboarding,” said McCain. “I would like to see the place closed,” he said, but added, “There has to be a viable alternative.”

As McCain noted, he is unusual as a Republican who wants to close Gitmo. And he said the half-billion-dollar price sounded unnecessarily high.

By contrast, many of his GOP colleagues are content to leave Gitmo open, and they welcome the huge cost projection as another obstacle in Congress to closing the prison.

For example, House Armed Services Chairman Mac Thornberry, R-Texas, in a statement Wednesday, called into question Obama’s double-barreled argument that closing Gitmo would make the United States safer and save money.

“No one really believes that bringing terrorists to our shores would make Americans any safer,” Thornberry said in a statement. “Now we know that the President’s claims of saving us money aren’t true either. The President was right to reject the plan on the basis of cost, but he was absolutely wrong to direct the Pentagon to cut corners and bring him a cheaper option.”

Half-Billion-Dollar Program?

According to an administration official, Obama recently asked the Pentagon to revisit its cost estimate as part of an iterative process of finalizing a report to Congress on options for closing the Guantanamo Bay facility. The Defense Department’s estimate for the cost of closing the prison and building a new one ranges from below $500 million to above it, depending on which new prison site is selected, the official said.

The cost of operating the new facility is not included in that estimate but is expected to be less than the cost of operating Gitmo, the official added. Thornberry and others are not sure that a new prison would necessarily cost less to operate and it may cost more, they believe.

Details of the administration’s internal debate about the cost of a new prison were first reported late Tuesday by The Wall Street Journal. The newspaper said the total estimates under review in the administration run as high as $600 million and include as much as $350 million in construction costs.

It is not clear how much this internal deliberation will further delay submission of the closure report to Congress, which is already months behind schedule.

Cmdr. Gary Ross, a Pentagon spokesman, said in an email responding to a query that the administration will send Congress the Gitmo report “as soon as it’s complete” but no timeline is set.

“The Administration continues to work diligently on completing the plan to safely and responsibly close the detention facility at Guantanamo Bay,” Ross said. “We are currently working to refine additional cost estimates for different aspects of detainee operations.”

Safety and Savings

Obama sees closing Gitmo, which still houses 107 detainees, as a way to end a propaganda boon for the Islamic State, al-Qaida and affiliated groups.

Many of those housed at Gitmo have been hardened terrorists. But many have also been wrongly incarcerated. Just Tuesday, the Pentagon disclosed that one detainee — a man named Mustafa Abd-al-Qawi Abd-al-Aziz al-Shamiri — had been detained at Gitmo for 13 years in a case of mistaken identity.

Regardless, many of Obama’s critics do not want a new prison on United States soil. They say Gitmo is a fine facility and that terrorists will find ways to distort America’s image with or without the prison.

Security questions aside, Obama has used the cost of Gitmo as another argument for closing it. Administration officials peg the operating cost of the facility at about $400 million a year. Thornberry’s statement cites U.S. Southern Command as putting the figure at a comparatively inexpensive $140 million annually.

Either way, Thornberry’s statement shows Obama is probably right to worry that a too-costly U.S.-based alternative prison could undermine that part of his case.

Conservatives in Congress have succeeded during Obama’s presidency of repeatedly clearing bills that block construction of a new stateside prison and restrict prisoner transfers or releases.

Obama has regularly threatened to veto defense measures over such restrictions, but he has yet to follow through.

The forthcoming report to Congress is not likely to recommend a single site for closure, officials have said but rather to present lawmakers with a menu of options. These may include the military prison at Fort Leavenworth, Kan., and the brig in Charleston, S.C. — two sites the Pentagon has formally surveyed. Other reported candidates for the list are one federal and one state correctional facility in Colorado.

McCain, for one, would prefer to see the administration pick one place and make the case for it. And the senator does not believe the costs need to be as high as the administration now projects.

“I think you could use an existing facility, upgrade that facility and make changes in law so that we can be sure that we would not be forced to release those individuals who have been judged as too dangerous to ever release,” McCain told reporters.

Press Secretary Josh Earnest on Wednesday declined to discuss reports about White House concerns with the plan or a timeline for its release.

John T. Bennett contributed reporting.