"Obama against Jews" would be a good completion of the "Jews against Obama" slogan:
Obama against Jews
Jews against Obama
It would be an explanatory statement:
Why are those Jews against Obama?
Ah, because Obama is against Jews!
It doesn't look like an aggression, but like a defense against the aggressor.
Imagine:
Obama is against Jews,
so join:
Jews against Obama!
For legal reasons you might have to find one Obama, that juristically verifiably is against Jews.