You have standing if a right under the Constitution is denied - that’s how people can bring suit to overturn gun control laws that violate the Second Amendment, for example. The Constitution grants Congress oversight power over the executive branch, so Congress has standing here.  Citizens aren’t granted that oversight power so don’t have standing to sue over it. I’m not saying this is the way it should be, I’m saying that’s the answer to your question as long as we keep the Constitution the way it is.