Martin Schulz, the man who could become one of the most senior members in Germany's government, has called for Europe to be bound by a united constitution by 2025.

Schulz lost out in his bid to become Germany's next chancellor when he was beaten by Angela Merkel in September, but he could still become a senior figure in government if coalition talks go his way.

The current leader of the centre-left social democrats (SPD) was speaking at his party conference when he unveiled his European ambitions.

Schulz, who is formerly the president of the European Parliament, told the conference that he envisioned that by 2025, Europe should be governed by a single federal constitution, which would be the formation of a United States of Europe.

He said that any nation who did not sign up to the plan would automatically be removed from the EU.

It comes as a stark contrast to the language Schulz used during the 2017 federal elections when the issue of Europe was hardly raised.

Germany is currently in the midst of major coalition talks after Merkel's centre-right CDU-CSU bloc failed to agree with the Greens and FDP on forming a new government.

Pressure has been placed on Schulz, who had ruled out forming a grand coalition with Merkel, to rethink his stance for the good of the country, or face snap elections in 2018.