President Obama is determined to close the prison at Guantanamo Bay, and if he decides to do so without Congress, there may be little his opponents can do to stop him.

Since his State of the Union Address Tuesday, the administration has sped up the effort significantly. Ten prisoners were transferred this week. Ninety-three prisoners remain, 34 of whom have been cleared for release.

On Thursday, Defense Secretary Ash Carter said he had sent a detailed plan to Obama laying out how to move the remaining prisoners to the United States. The White House is to submit that plan to Congress soon.

That strategy directly challenges existing laws that not only prevent Obama from moving Guantanamo prisoners to US soil, but also bar the Pentagon from spending congressionally appropriated funds to do so. Obama, in a series of signing statements, has consistently rejected the validity of those laws, arguing they infringe upon the executive’s powers.

Military law experts told us that if the White House defies Congress, lawmakers’ options for stopping Obama are limited.

“It would be difficult for anyone to intervene,” said Rachel VanLandingham, a professor at Southwestern Law School who served as a judge advocate in the Air Force. “If he really wanted to do it, he could, but it would come at a huge political cost.”

That cost could include a long court battle over the constitutional separation of powers. But the federal courts are unlikely to intervene quickly because it’s largely a political issue, several experts said, meaning that the Obama administration would be history before a final ruling on the legality of its approach. And at that point, the prison could already be closed.

Congressional leaders, including House Speaker Paul Ryan, have said the president’s anticipated action could amount to asking the US military to break the law, but the military is not likely to see it that way. “Military members are required to follow all lawful orders, but there’s a legal presumption that orders are lawful,” said VanLandingham. “The military is going to salute smartly.”

Congress’ record on stopping Obama from releasing prisoners is not strong. Congression­al leaders were incensed when in 2014 the president used executive authority to release five Taliban commanders from Guantanamo to trade them for US Army soldier Bowe Bergdahl, who is now set to stand trial for desertion.

In December, House Armed Services Committee Republicans issued a report that said Obama violated a statute that required a 30-day notification to Congress on the transfer of any detainees. The Government Accountability Office agreed and added that the Pentagon misused funds for the transfer.

Southcom commander Gen. John Kelly said last week that the military was directed to transfer the Taliban five secretly, without alerting reporters on the base. “It was a dicey transfer,” he said. “All of us were down there. We were doing the transfer, and we never got caught.”

Obama has come close to saying he will shut the prison with or without congressional approval. At his year-end press conference, the president said, “We will wait until Congress has definitively said no to a well-thought-out plan with numbers attached to it before we say anything definitive about my executive authority here.”

On Tuesday morning, White House Chief of Staff Denis McDonough told reporters that the president would employ “audacious executive action” for the rest of the year, on several issues that could include Guantanamo Bay. He said the main question Obama will use when considering whether to use executive action is, “Why not?”

Asked about Obama’s plans to close the prison, Senate Majority Leader Mitch McConnell said Tuesday, “Hopefully, he will fail.”

The ranking Democrat on the Senate Intelligence Committee, Dianne Feinstein, who was against the Bergdahl trade, told us this week the prison should be closed.

The wild card is Senate Armed Services Committee Chairman John McCain. This week, he told us he was open to considering the plan but skeptical anything the White House submits can get Republican support.

“I would support presenting it to my colleagues to see if we could get a majority vote,” said McCain. “There’s been so much unilateral action that there’s a lot of anger about this.”

When it comes to Guantanamo, the president’s “lame duck” status is a misnomer. Politically, he is now free to act without Congress. But he may spawn a new problem: a court battle over the constitutional separation of powers.