Tue Jul 8, 9:32 PM ET

Berlin Mayor Klaus Wowereit (L) jokes with U.S. actor Sylvester Stallone during a reception at the town hall in this February 3, 2004 file photo. Some on the left think Wowereit might be the best hope to give the SPD a lift in the way Barack Obama’s historic candidacy has helped boost the U.S. Democrats. Wowereit is the most popular elected leader in the SPD and the party’s most charismatic national figure.

To match feature GERMANY-WOWEREIT/ REUTERS/Fabrizio Bensch/Files (GERMANY)