Heteborn, a village at the northern edge of the Harz, is the home ground of Sven Schulze, a CDU politician who came up short at the polls. Even here, more than half of voters backed the AfD. Schulze grew up in the village, which makes his defeat on familiar turf stand out. Locals and observers are now asking what is pulling voters, even in a candidate's own backyard, toward the party.