Personally I would not put up with any of this nonsence, our little cockers are tough little B#*g#-s, give him a dam good tug, he will have to walk in the end or end up with a sore bum ! He is testing you to see just exactly what he can get out of this situation. Don't tolerate this behaviour and be firm with him.
Sometimes we have to go right back to very basic training, I never give treats for rewards just a genlte touch and a soft word.