European Commission President Jean-Claude Juncker | Thierry Charlier/AFP via Getty Images Jean-Claude Juncker: Turkey’s not ready for EU membership Commission president “cautiously optimistic” of summit deal on refugees.

Turkey won't be ready for EU membership for ten years or more, the president of the European Commission said in an interview published Wednesday evening.

"Turkey is currently not ready for accession," Jean-Claude Juncker told German paper, Handelsblatt. "I think that won’t be the case in 10 years either.”

Ankara has made unfreezing its EU accession process one element of a deal to take back migrants and refugees from Europe, which EU leaders hope to finalize at a summit on Thursday and Friday.

Juncker said Wednesday that he is "cautiously optimistic" a binding deal will be reached at the summit. However, Turkey's attempt to unfreeze its EU membership application is a major sticking point.

A draft document to be discussed with Turkish Prime Minister Ahmet Davutoğlu at the summit, promises only to open new areas of negotiation on Turkish membership "soon."

Leaders, such as European Parliament President Martin Schulz have said the refugee deal and Turkey's EU aspirations must be kept separate. German Chancellor Angela Merkel said in January, before the current deal was put on the table, that it is "not realistic" to give a time-frame for when Turkey can expect to join.

European Council President Donald Tusk traveled to Cyprus ahead of the summit this week, the EU state most opposed to opening a path for Turkey to enter the bloc.