The circles are a great idea, BUT if you are already playing "keep-up" in a group, the circles are going to upset him even more. (He will be even FARTHER behind after doing some circles...) Unless, like mentioned by everyone you have some patient friends that will stop, but then he is catching up anyways. (ALWAYS CHASING OUR TAILS in this game of horses!!)
PLEASE, don't get frustrated. He can't help his desire to want "be out front." That is why the leap frog is so effective. You give him a chance to relax (FIRST) out front at the walk, trot and canter....then take the lead away by having a friend walk/trot/canter along side until he can relax at that spot. All the while giving him the lead back and slowly taking it away.. (this IS a lengthy process, but WELL worth it). Then work on letting the horse PASS you, take it back, (I am sure you get the idea.)
You are just letting him know it it OK to have the lead, give it away, it will come back....I have spend HOURS doing this and I am sure I will spend more hours with different horses. If your friends get impatient, then they aren't friends!
I am sure ANY horse person that respects safety will be more than willing to help you out.
Let me know if this works for you and I TOTALLY feel for you!! Please be patient though, it will pay off I promise!!!