I once had to back a horse up out on a hack for a good 300-400 yards. The horse didn't want to go forward, so I said fine, have it your way, we'll do the hack in reverse. She rethought her decision when I gave her a chance to move forward; she never gave me another problem about going out on a hack.
I resort to this technique quite often when a horse doesn't want to move forward. Just turn them around and back them up to get passed whatever they don't want to pass. It has always worked for me and they quickly learn it is easier to move forward then backwards.
This is what happens when you have democrats in office