I've intimidated him on every playthrough, I didn't even know there was another way, he's always very friendly after I kill the snakesHe wouldn't be to happy about your forced help though... it's better to make him cooperate by being a good friend
Edit: Curses to slow page refreshes
PS nobody answered my question about not getting all the votes, does the game continue to the duel if you don't get 100% support or does the election trigger simply fail to trigger until you get all the votes?