So why don't we just drill in Alaska?

I hear we have oil reserves there, and also reserves in the Gulf of Mexico that would last a LONG time.
The only answer I’ve gotten as to why we can’t drill in Alaska is “It’s because of the Environmentalists.”

But it can’t be! Do they really have THAT much power? There’s gotta be something else. And if it is them, I’m angry at them because I hate paying so much for gas.