They may be slowly starting to realize that Obama's pro-Islam attitude may serve as a green light to Muslims (and anti-Semites in general) in the US to attack Jews.
Dennis Prager talks about this phenomenon. These people have lived here for so long they've forgotten what Jews have suffered for many centuries, and confuse those of us on the right with the instigators of pogroms. They love socialism, worship Democrats and wish communism well.
Only when their own scalps are directly threatened will they consider a different way. I'm not sure they will ever turn on Obama, but voting for him was a moment of supreme stupidity on the part of American Jews.