Mr Bachmann stepped down just as tens of thousands of people were expected to rally in the eastern city of Leipzig for the latest Pegida rally.
Prosecutors are investigating insulting comments about refugees attributed to him by German newspapers.
A Pegida spokeswoman sought to play down the Facebook photo as a "joke".
But the German government condemned the photo. Vice-Chancellor Sigmar Gabriel told Bild: "Anyone in politics who poses as Hitler is either a total idiot or a Nazi. Reasonable people do not follow idiots, and decent people don't follow Nazis." » | Wednesday, January 21, 2015
