It's not so much that the puppy pulls (ALL sporting dog puppies pull) but that Obama obviously doesn't have the slightest idea how to walk a dog.
This is how you deal with a puller:
This is my middle dog, Ruby, as a young pup, first being introduced to retrieving in the water. She was basically out of her mind at the moment the pic was taken.
Center of gravity is the key, you keep your weight back. Ideally I'd have both hands on the check cord, but my other hand is occupied (I haven't even thrown the bumper yet, and she's already certifiable).
Once the dog gets your upper body out ahead of your center of gravity, you're pretty much doomed . . . .