Washington ? White House aides are increasingly convinced that accused 9/11 mastermind Khalid Sheikh Mohammed will never face trial in a civilian court and are trying to cut a deal that would still transfer Guantanamo Bay terrorism suspects to the U.S., where many would face criminal charges, a senior administration official said Monday.

President Barack Obama is trying to keep a campaign pledge to close the U.S. military prison in Cuba, a promise that has attracted criticism from Republicans who say it would jeopardize national security. He has also lately been under fire from people within his party who say Obama should not accept any deal that would prosecute Mohammed outside the normal judicial system.

But a senior official, speaking on condition of anonymity to discuss the sensitive negotiations, said the most important goals are closing Guantanamo Bay and ensuring that the government can prosecute some detainees in U.S. courts. To do so, the only option may be abandoning the administration’s original plan to prosecute the alleged 9/11 conspirators in civilian courts and instead send them before military tribunals.