BERLIN — Millions of Germans will head to the polls in a federal election on Sunday that will determine who will succeed Angela Merkel after 16 years as Germany's chancellor. According to the latest polls, Germany's center-left Social Democratic Party is narrowly ahead of Merkel's center-right Christian Democratic Union (CDU) and its Bavarian partner, the Christian Social Union. They're closely followed by the Greens, the far-right Alternative for Germany and the libertarian Free Democratic Party, all holding onto double-digit poll numbers going into Sunday's election. Josef Janning, a senior associate fellow with the German Council on Foreign Relations, says the...