Carry the leash around with you for a couple of days. Sit down on the floor in the kitchen and put it on him. Sit on the cammode and put it on him. See if it makes a difference if you tell him to sit first, and then put it on him -- he might not be ready for that though if he does not have sit, down. See if it makes a difference if you put it on him while you are sitting down on his level.
I don't think you will have to do that forever (if it works). He is just going through a phase and he should grow out of it. Don't make a big deal about it, actually ignore the behavior, clean it up good. He should get over it quicker if you do not make a big deal about it.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC