If only it were that easy. The president doesn't have a magic "get things done" button, unfortunately. He must pass everything through congress. That's the entire issue with the debt ceiling. If he cannot act - whatever the action, then we will default.
Actually he does have the right to prioritize spending in such an instance and therefore does not need congressional approval. It's a power of the Treasury Secretary. Clinton did it in '95 during the government shutdown.
