Short of impeachment, there is really nothing Congress can do.
From National Review Online, by Andrew C. McCarthy, 01/17/15 –
You’re not going to like this.
Our commander-in-chief is recklessly releasing jihadists from Guantanamo Bay. The president’s Bush-deranged base is buoyed by the all-out effort to fulfill his vow to shut down the detention camp. But the vast majority of Americans remain opposed, and increasingly alarmed. The pace of releases has surged since November’s midterm elections, with over two-dozen detainees sprung — aiding the enemy even as the terror threat intensifies.
But if you want it stopped, the president has to be impeached.