In a renewed Democratic effort to close the prison at Guantánamo Bay, Sen. Dianne Feinstein released an independent feasibility study that showed six military prisons on U.S. soil could absorb the 166 detainees held in Cuba — then the White House Thursday called Congressional limits on detainee transfers “misguided.”

The nonpartisan Government Accountability Office delivered the 68-page report to Feinstein on Nov. 14, a week after President Barack Obama’s re-election. Feinstein, a Democrat from California and chair of the Select Committee on Intelligence, released it Wednesday night.

It includes no recommendation on the wisdom of dismantling the decade-old detention center run by 1,700 Pentagon employees and contractors but shows how transfers to U.S. soil could be accomplished using existing military or federal prisons.

Some facilities would have to be retrofitted. Some U.S. prisoners would have to be moved because international and military law forbids holding war prisoners in the same place as convicts. And new policies would have to be established, for example, to accommodate visits by the International Committee of the Red Cross.

Any Obama administration effort to move Guantánamo captives now, Sen. John McCain told Fox News on Wednesday night, “would be very hotly contested.” Any unilateral effort by the White House “would be basically an assertion of the Executive Authority that clearly would be violating existing laws,” said McCain, an Arizona Republican.

Obama ordered the prison emptied by Jan. 22, 2010, a goal Congress thwarted through legislation that prevented transfers to U.S. soil for detention or trial.

White House officials would not say Thursday whether Obama intended to assert executive authority to make such a move.

“We still believe that it’s in our national security interest to close the prison at Guantánamo Bay,” White House spokesman Tommy Vietor said Thursday from the National Security Council. “We are reviewing the report.”

Feinstein released the report with a statement that said it “demonstrates that if the political will exists, we could finally close Guantánamo without imperiling our national security.”

At the same time, the White House Office of Management and Budget issued a statement decrying as “misguided” continued limits on transfers from Guantánamo.

“Since these restrictions have been on the books, they have limited the Executive’s ability to manage military operations in an ongoing armed conflict,” the OMB statement said, suggesting a veto threat of new straitjacketing legislation contained in the 2013 National Defense Authorization Act.

The restrictions also “harmed the country’s diplomatic relations with allies and counterterrorism partners, and provided no benefit whatsoever to our national security,” the OMB statement said.

The GAO report did not say transfers of detainees to U.S. soil would be simple. But it identified six U.S. military lockups where all of the foreign men now held at the prison camps could be moved: U.S. Navy brigs in Miramar, Calif., Charleston, S.C., and Chesapeake Va., as well as two Army lockups at Fort Leavenworth in Kansas and another Army detention facility at a joint Army-Air Force base in Washington called Lewis-McChord.