I don't know what point the other sticker is trying to say, other than "Democrats fight racism*, so vote Republican." Well, I still don't know because it doesn't make very much since, like all these stupid consie bumper stickers.
It's trying to say "Fight racism by voting Republican" because of this meme going around that because the KKK were founded by democrats, that the democratic party is the party of racists.
I don't think it's trying to say that: that particular argument is almost always specifically tailored towards Blacks, and there is no evidence of that here. In fact, given the inferred hostility to African descent in the other bumper sticker, the audience is probably White. There are a few other possibilities that I think more likely.
I think it is most likely referring to the large amount of support among Black Americans for President Obama. The driver probably perceives this support as the result of an unsubstantiated racial preference among Black Americans, i.e., as the result of what he would call racism against White people.
It could also be a plug against affirmative action. In this case, the driver sees himself and his race as losing out against racial minorities in institutionalized racial preferences. He would call it reverse discrimination, and see it as racism against Whites.