The Nazis took control because of a Splintered Left into multiple factions while the Right was united. The Nazis came for the communists first while the moderates watched, because the communists and moderates were almost as much each others enemies as the Nazis were.

Look to this example and think of a way to gain support and build trust. Find a way to show people of all different ideologies how horrible these events are and how their loved ones could be next regardless of their own beliefs or their own skin color.