A great Vox article summarizing the Green Lantern Theory of the presidency:
The Founding Fathers were rebelling against an out-of-control monarch. So they constructed a political system with a powerful legislature and a relatively weak executive. The result is that the US President has little formal power to make Congress do anything. He can’t force Congress to vote on a bill. He can’t force Congress to pass a bill. And even if he vetoes a bill Congress can simply overturn his veto. So in direct confrontations with Congress — and that describes much of American politics these days — the president has few options.
If you’ve ever wondered why the President doesn’t just invade this or repeal that or privatize this or socialize that, you may be part of the Presidential Green Lantern Corps without even knowing it.