BRUSSELS (Reuters) - The European Commission on Wednesday appointed Martin Selmayr, EC President Jean-Claude Juncker’s top aide, as Secretary-General of the Commission -- the highest civil servant job in the EU executive.

The surprise appointment will put Selmayr, 47, whose role as power-broker behind the scenes has made him one of the most powerful players in Brussels institutions, at the head of an army of 32,000 EU staff.

A German lawyer by education who is credited with organizing the campaign that brought Juncker the job of EC president, Selmayr will replace Alexander Italianer, a 61-year old Dutchman who has been with the Commission since 1985.

EU officials said Selmayr, whose role as Juncker’s right-hand man behind the scenes has earned him many enemies, was very unpopular among many Commission officials and EU member states’ envoys, and his future after Juncker departs in November 2019 had been uncertain.

His appointment suggests he might now stay on after that.

“The College has decided to appoint Martin Selmayr, the current head of cabinet of the President, as the new Secretary-General of the Commission,” the Commission said in a statement.

“This decision will take effect on 1 March. At the same time, President Juncker has decided that his current Deputy Head of Cabinet, Clara Martinez Alberola, will become his new Head of Cabinet,” the Commission said.

The EU officials, who spoke on condition of anonymity, said Selmayr’s appointment would make it more difficult to remove him from the EU bureaucracy after Juncker goes.

But Juncker told a news conference it would be down to the next head of the EU Commission to confirm whether to keep Selmayr, who will be responsible for coherence of shaping new policies and steering them through other EU institutions, in the job.

Officials in Brussels speculate the next Commission head could be French -- either the current chief Brexit negotiator Michel Barnier or International Monetary Fund chief Christine Lagarde.

Selmayr worked for the European Central Bank from 1998 to 2000 and in 2000 joined the media conglomerate Bertelsmann as a legal adviser. He started working for the Commission in 2004.