The President of the European Parliament has told ITV News that Britain should stay in the European Union - as it belongs to it.
Martin Schulz is in the UK to meet with the Prime Minister to discuss his proposals tomorrow.
Schulz said he was looking forward to hearing what Mr Cameron has to say but refused to use the term "UK relationship" with the EU.
"You cannot have a relationship with yourself. The EU is and Britain are one thing. The UK belongs to the EU."
ITV News asked whether it was possible for Cameron to change the UK's relationship with the EU.
"Nothing is possible for the time being. We have to wait and then we discuss," Schulz replied.
He said important member states like the UK have the right to discuss their role within the EU.
But he warned the moment Britain put a treaty on the table other countries in the EU would want to do the same.