I would start at home and MAKE him go. I had a horse try to pull such a stunt once, the I'm Not Going To Move and You Can't Make Me. I cracked the whip across the meaty part of his hindquarters (after a half hour of asking with increasing firmness) and SCREAMED at him. You bet your buns he moved!
I lunged him aggressively, sudden lead changes, faster, slower, stop, go, stop, go. I did this for ten minuets and when I was done, he was begging to be asked nicely again. The next time I lunged him, he moved off on the first, gentle, request.
Just get out there, stick out your chest, and declare that YOU are the leader and HE WILL LISTEN. I also found for a stubborn horse, a plastic bag works wonders. With Sam (one I mentioned before) he was well trained and laughed at such things, so I got aggressive with him. I only had to do it once.
your horse, but act like the cranky old lead mare. If you don't move, I'm going to bite you. If you still don't move, I'm presenting my rear end and I'm going to kick you clear back into yesterday.
If he tries to buck, charge, or kick, make him work even harder. Scream and shout and have an utter hissy fit. Make him horrible uncomfortable. If he turns those hindquarters towards you, smack them. Hard. If you back off when he says "I'm the boss" then your saying to him, "Sorry, right, your the boss" and he'll just keep getting worse.
Make your way the way of sunshine and butterflies, and make his way the way of sweating and lack of air