Martin Selmayr, the chief of staff to European Commission President Jean-Claude Juncker, did not mince his words when he said the UK’s decision to leave the European Union was “stupid”.

“Brexit is bad, and it’s a stupid decision,” Selmayr said at a conference in Brussels on September 4. “The only people who can reverse it would be the British people and I am not a dreamer, I am a realist. Brexit will happen on March 29, 2019.”

As reported by Bloomberg, German official Selmayr is one of the most powerful people in the EU hierarchy. His remarks came just two days after the bloc’s chief Brexit negotiator, Michel Barnier, was quoted by UK media as saying that British people need to be “educated” about the price they’ll pay for their decision.

The UK  and EU are embroiled in increasingly bad-tempered negotiations over the terms of Britain’s withdrawal. The British government is refusing to accept that it has financial obligations beyond its regular annual membership fees; in return, the EU is refusing to open talks on a future trade arrangement.

Selmayr said that while it was “legally” possible for the UK to reverse its decision, “it would be arrogant of us” to say the EU could force it to happen.

“The door of the European Union after March 2019 will always be open, and to all of our British friends, of course that is something that we humanly wish,” Selmayr said. “But politically at the moment this option is not on the table.”

According to Bloomberg, time is running out for the UK to get a deal on arrangements for its departure from the EU, with complex separation issues, the money argument and a plan for a transition period far from being resolved. It’ll leave the bloc in 19 months whether it has managed to get a deal or not.