With all the top jobs at the European Union coming open, EU leaders gathered Thursday for a major bout of political horse-trading, trying to pick candidates who will have a major impact on the bloc over the next five to eight years while keeping its 28 nations happy. That’s not an easy task. The EU is responsible for coordinating common policies on sectors ranging from the single market to agriculture, from competition issues to immigration. The main posts up for grabs Thursday are the head of the EU’s powerful executive arm, the European Commission — now held by Jean-Claude Juncker — and the president of the European Council, the body that represents the member states in Brussels. That position is currently held by Donald Tusk. Other key jobs to be filled include the president of the European Parliament, chairman of the European Central Bank and the EU foreign policy chief. The EU’s parliament must endorse some of the posts. French President Emmanuel Macron hit Brussels early for a series of meetings, hours before the summit started, meeting with several European leaders and holding talks with German Chancellor Angela Merkel. That set off a chain reaction of informal huddles involving Merkel — leader of the EU’s biggest power — to weigh up potential candidates based on their political affiliation, nationality and gender, and perhaps their diplomatic acumen. Merkel said this two-day summit might not necessarily succeed in filling all top jobs at stake, an issue that has divided the 28 members….