He obviously thinks he's the alpha dog, not you.
He has to be taught that YOU go out the door before him or he doesn't go out at all. Cesar Milan had a show about this not so long ago and it just requires you working diligently with him. Doorbell rings...SIT. STAY. And every time you go out together you go out the door first, not little Mr. Bossypants. LOL. Good luck.