The name Friedrich Merz is on none of the 5.2 million ballot papers in circulation on Sunday, when voters choose two new German state governments, yet the deeply unpopular 70-year-old federal leader will be a crucial factor in both polls.Very different parliaments are likely to emerge for the city-state of Berlin and the northeastern Baltic state of Mecklenburg-Vorpommen. Yet either – or both – could deliver credibility blows to Merz and his centre-right Christian Democratic Union (CDU).In the Baltic Sea state of Mecklenburg-Vorpommern, where the local CDU has struggled for years, Merz’s party will be lucky to clear the five...