The leader of Germany's main socialist party has called for a United States of Europe by 2025.
Martin Schulz said any countries who disagree should follow Britain's example and leave the bloc.
He made the plea in a speech to 600 of his Social Democrats at a congress to decide whether to start coalition talks with Angela Merkel's party.
Martin Schulz said any countries who disagree with a federal Europe should follow Britain's example and leave the bloc
He said: 'I want a European constitutional treaty that creates a federal Europe'.
The treaty would then be presented to all member states for ratification, with those that reject it automatically leaving the bloc, he said.
He suggested a target year of 2025, one century after the SPD first spoke of a future 'United States of Europe'.
Schulz said only a more united EU could meet challenges such as combating climate change or managing mass migration, forcing internet giants such as Google